Developing Pest and Fertility Best Practices for Industrial Hemp

Final report for ONE19-333

Project Type: Partnership
Funds awarded in 2019: $29,973.00
Projected End Date: 12/31/2021
Grant Recipient: University of Vermont
Region: Northeast
State: Vermont
Project Leader:
Dr. Heather Darby
University of Vermont Extension
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Project Information

Summary:

Hemp, a non-psychoactive variety of Cannabis sativa L, is a crop of historical importance and is re-emerging as a popular crop as it is sought out for a wide variety of consumer and industrial products. As the acreage of hemp increases in Vermont and growing practices are established, the impacts on crop loss due to lack of/or improper fertility, disease, and pest management are becoming more evident. The objectives of this project were to understand nitrogen demands of hemp, identify biofungicides to manage fungal diseases of hemp, and to qualify the species composition of arthropod and disease pests in hemp. 

Research trials were conducted in 2020 and 2021 in Alburgh, VT. Nitrogen rates ranging from 0 to 200 lbs per acre were applied to hemp and the impact on hemp yield and cannabinoid concentrations were assessed. Nitrogen rates within this study impacted hemp flower dry matter yields, with those treatments receiving 100 and 150 lbs N ac-1 resulting in highest yields. Additionally, unmarketable flower appeared to be positively impacted by additional nitrogen applications with the highest rate having the lowest amount of unmarketable flower material and the control having the highest amount of unmarketable flower material. In 2020, increased nitrogen application rates led to depressions in cannabinoid concentrations with a nearly 4% difference between 150 lbs N ac-1 rates and control rates receiving no additional nitrogen. In 2021, there was no impact on cannabinoid concentrations. Further research needs to be conducted to determine optimum rates of nitrogen for hemp. Given the dynamic nature of nitrogen a in-season test would be beneficial to growers. 

There were 4 biofungicides evaluated for the control of disease on hemp grown outdoor and in a low-tunnel. Overall disease pressure was relatively low due to dry weather conditions. Disease pressure was significantly lower when hemp was grown in the low-tunnel and was protected from precipitation and moisture. With the exception of Kocide (a copper based product), the biofungicides did not differ from the control. The Kocide, provided excellent control of leafspots compared to the other treatments. Unfortunately, this product also led to copper accumulation in the harvested hemp flower. This may lead to rejection in the market place. Additional research needs to be conducted to test potential control options for disease in hemp. 

An assessment of disease and arthropods in hemp throughout the northeast revealed a variety of pests colonizing hemp throughout the season. The primary diseases included leafspots, Botrytis, and powdery mildew. Common arthropod pests included aphids and leafhoppers seen throughout all locations. In most cases disease and arthropod pressure were low. It is expected that diversity and severity of pests will continue to increase as hemp production expands on the landscape.  Outreach needs to be continued to help farmers implement scouting and monitoring to properly identify news and emerging pests.  Further research needs to developed to help farmers manage and control hemp diseases with integrated pest management.

Educational materials including production guides, research reports, and webinars were created throughout the duration of the project. Materials were delivered to over 400 stakeholders from 10 states that participated in outreach events. As a result 75 farmers reported making changes to pest and fertility management on their hemp farms. 

 

Project Objectives:

This project sought to understand production challenges industrial hemp growers face in the Northeast and begin to develop best management practices related to nutrient and pest management. The objectives of this project were to:

1. Develop optimum nitrogen rates for fertilizing industrial hemp in the Northeast.

2. Identify viable biofungicides that control fungal diseases of hemp. 

3. Qualify the species composition of arthropod and disease pest on industrial hemp on Vermont farms and quantify the impact of arthropod pests on industrial hemp. 

 

Introduction:

Hemp, a non-psychoactive variety of Cannabis sativa L, is a crop of historical importance and is re-emerging as a popular crop as it is sought out for a wide variety of consumer and industrial products. Hemp production is a rapidly growing industry in Vermont. In 2013, the Vermont state legislation established a regulatory framework for Vermont hemp farmers and in 2014, nine farmers registered with the state to grow 17 acres. Between 2019 and 2021 (the duration of this project), the number of registered hemp growers in Vermont ranged from 300 to  76 (Vermont Agency of Agriculture, personal communication). The majority of the hemp grown in Vermont is grown for cannabidiol (CBD) oil production although acres are increasing for both fiber and grain.

As the acreage of hemp increases in Vermont and growing practices are established, the impacts on crop loss due to lack of/or improper fertility, disease, and pest management have become more evident. Typically, hemp growers are not from farm backgrounds and have minimal understanding of basic crop management including the ability to identify and manage pests.

With the passing of the 2018 Farm Bill, industrial hemp is now removed from the list of controlled substances and is considered a legal agricultural crop. The industry is growing rapidly and scientifically based research and education is critical to farmers succeeding with this new crop. According to a survey from the UVM Industrial Hemp Conference (February 8th, 2019), 88% of respondents (n=136), were new to the hemp industry. In this survey, hemp growers and industry members also indicated they needed to know more about pest management (34%) and soil management (55%) to be successful in hemp production. The respondents also emphasized the need for research based credible production information to help grow a sustainable hemp industry.

Given the statewide expansion of the crop, it is imperative to scout and survey hemp in many locations and expand agronomic research to meet the immediate needs of growers. Pest damage and diseases and improper fertility management affect the health of the plant and the quality of the product produced. Foliar diseases reduce photosynthetic leaf area, use nutrients, and increase respiration and transpiration within the infected plant tissues. A diseased plant typically exhibits reduced vigor, growth and quality. In rainy years there may be total crop loss due to fungal diseases. Arthropod pests can directly damage crops, reduce vigor and act as vectors to spread disease.

As the industrial hemp industry continues to evolve, it is important that farmers are ready for the challenges that accompany the crop.  The goal is to limit the risk a farmer faces by developing sound agronomic and pest management strategies that help farmers produce high yield and quality crops.

Previous to 2014, hemp had not been grown in the US since The Marihuana Tax Act of 1937 made cannabis, including non-psychoactive hemp, illegal at the federal level. Much of the agronomic information to grow hemp has been lost or is long-outdated. In order to successfully grow hemp that will meet quality standards and allow farmers to make a profit, it is important to understand fertility requirements and potential pest pressure. The federal ban on cannabis has greatly impacted the amount of research that has been performed in the US. Therefore, little information exists on best management practices, especially specific to the Northeast region. Since the 2014 Farm Bill, several universities in the Northeast have started research programs including University of Vermont, Cornell, Penn State University, and University of Connecticut. However, these research programs have been very limited in scope primarily focusing on variety, seeding rate, and planting date for grain production.

There is almost no understanding of effective fertility management and viable treatments when disease and pest problems occur. This information is of vital importance to farmers in the Northeast successfully grow high quality hemp.

Pest Management

There is strikingly little research on integrated pest management for the production of industrial hemp. European corn borers, hemp borers, and beetles lay their larva inside the stems, which feed on and weaken plant structure, potentially causing it to break (McPartland 1996b). When these insects severely damage the plant, yields decrease and seed development is prevented. Aphids, leafhoppers, and tarnished plant bugs suck fluids from the phloem, resulting in stunted growth and wilting.

Information on insect pests of hemp exists specific to regions such as Pakistan, (Mushtaque et al. 1973, Baloch et. al 1974), India (Nair & Ponnappa 1974), New Zealand (McPartland & Rhoda 2005), Canada (Canadian Hemp Trade Alliance 2017, Baxter & Scheifele 2009), and in the western US (Cranshaw & Schreiner 2019). Current insect surveys and scouting guides for North America are primarily focused on western regions (Cranshaw & Schreiner 2019). A survey of insect pests in New York was compiled in 2018 (Chartand, 2018). There is a lack of information and research on common hemp pests in New England.

Dr Darby and her team have collected preliminary data on arthropod populations via scouting their industrial hemp research trials at Borderview Research Farm in Alburgh, VT (Darby et. al 2017a-d, Darby et. al 2018a-c, Darby 2018). Thus far arthropods appear to cause minimal damage to plants. However, statewide assessments of disease and arthropods have not been completed in Vermont or the region. There is a need to research and compile information about the most common pests industrial hemp growers in northern New England will encounter, and what damage they may cause the crop. This research is critical to formulating best management practices for mitigating pests in the northeast, and to disseminate that information to farmers.

There is also a lack of information on the use of fungicides to manage disease. The fungal diseases most frequently observed on hemp include botrytis, or grey mold (Botrytis cinerea) and white mold (Sclerotinia sclerotiorum). (Baxter & Scheifele 2009, Punja et. al 2018). Grey mold thrives in temperate climates with cool to moderate temperatures, and has the potential to destroy the crop. Grey mold causes damping off in seedlings, chlorotic stems, cankers, and wilting (McPartland, 1996a). Fusarium and powdery mildew have also been found on hemp (Baxter & Scheifele 2009). The few fungicide trials conducted took place in the Netherlands (Van der Werf 1991, Van der Werf, & Van Geel 1994) and Manitoba (Kostuik et. al 2014). There are currently no pesticides approved for specific use on hemp in the U.S., and more research is needed.

Fertility Management

The majority of hemp fertility studies have been conducted in Europe (Amaducci et. al 2001, Campiglia et. al 2017, Iványi & Izsáki, 2009, Finnan & Burke 2013), and North American studies have primarily been conducted in Canadian provinces (Aubin et al. 2015, Vera et. al 2010). PennState Extension began to assess fertility in industrial hemp trials in 2017 (Roth, 2018). All of this research has been conducted on hemp being produced for grain or fiber. There even more limited information on fertility management for hemp being produced for CBD oil. Farmers are interested in rates and types of amendments that will meet the fertility needs of hemp crops. Cover cropping has the potential to provide numerous benefits including nutrient retention, improvement of soil structure, weed suppression, and disease control (Clark, 2008). Within hemp production systems, the use of various cultural control practices can be used with the aim of maximizing air flow and reducing weed competition while providing positive impacts on soil health and nutrient management. Overall, more research is needed, along with recommendations and guidelines specific for the Northeast.

Development of effective nutrient and pest management options would be critical information for growers to optimize crop quality and yield.

Amaducci S, Errani M, Venturi G. (2001). Response of Hemp to Plant Population and Nitrogen Fertilization. Italian Journal of Agronomy. 6(2): 103-111.

Aubin, M., Seguin, P., Vanasse, A., Tremblay, G.F., Mustafa, A.F., and Charron, J. (2015). Industrial Hemp Response to Nitrogen, Phosphorus, and Potassium Fertilization. Crop, Forage & Turfgrass Management 1:2015-0159.

Baloch G.M., M. Mushtaque and M.A. Ghani, (1974). Natural enemies of Papaver spp. and Cannabis sativa. Annual report, Commonwealth Institute of Biological Control, Pakistan station, pp. 56-57.

Baxter W.J. & Scheifele, G. (2009). Growing Industrial Hemp in Ontario. (Report number 00-067). Ontario Ministry of Agriculture, Food, and Rural Affairs. Retrieved from: http://www.omafra.gov.on.ca/english/crops/facts/00-067.htm#diseases 

Benelli, Pavela, Petrelli, Cappellacci, Santini, Fiorini, Sut, Dall’acqua, Canale, Maggi. (2018). The essential oil from industrial hemp (Cannabis sativa L.) by-products as an effective tool for insect pest management in organic crops. Industrial Crops & Products, 122: 308-315.

Campiglia E., Radicetti E., Mancinelli R. (2017). Plant density and nitrogen fertilization affect agronomic performance of industrial hemp (Cannabis sativa L.) in Mediterranean environment. Industrial Crops and Products.100:246-254.

Canadian Hemp Trade Alliance. (2017). Hemp Production eGuide: http://www.hemptrade.ca/eguide/production/insects-and-pests . Accessed 5 April 2019.

Chartrand, M. (2018). Insect Pest of Industrial Hemp in NYS. Cornell Cooperative Extension. Cornell College of Agriculture and Life Sciences. 

Clark, A. (Ed.). (2008). Managing cover crops profitably. Diane Publishing.

Cranshaw W., Schreiner M. (2019). Insect Management Considerations in Hemp Production. Department of Bioagricultural Sciences and Pest Management, Colorado State University.

Darby, H. (2018). 2018 Industrial Hemp Grain Variety Trial. University of Vermont Extension. Retrieved from: https://www.uvm.edu/extension/nwcrops/research

Darby, H., Gupta, A., Cummings, E., Ruhl, L., & Ziegler, S. (2017a). Industrial Hemp Fiber Variety Trial. University of Vermont Extension. Retrieved from: https://www.uvm.edu/extension/nwcrops/research

Darby, H., Gupta, A., Cummings, E., Ruhl, L., & Ziegler, S. (2017b). Industrial Grain Hemp Variety Trial. University of Vermont Extension. Retrieved from: https://www.uvm.edu/extension/nwcrops/research

Darby, H., Gupta, A., Cummings, E., Ruhl, L., & Ziegler, S. (2017c). Industrial Grain Hemp Planting Date Trial. University of Vermont Extension. Retrieved from: https://www.uvm.edu/extension/nwcrops/research

Darby, H., Gupta, A., Ruhl, L., Cummings, E., & Ziegler, S. (2017d). Industrial Hemp Fiber Planting Date Trial. University of Vermont Extension. Retrieved from: https://www.uvm.edu/extension/nwcrops/research

Darby, H., Gupta, A., Ruhl, L., Ziegler, S. (2018c). 2018 Industrial Hemp Grain Planting Date Trial. University of Vermont Extension. Retrieved from: https://www.uvm.edu/extension/nwcrops/research

Darby, H., Ruhl, L., Ziegler, S. (2018a). 2018 Industrial Hemp Fiber Planting Date Trial. University of Vermont Extension. Retrieved from: https://www.uvm.edu/extension/nwcrops/research

Darby, H., Ruhl, L., Ziegler, S. (2018b). 2018 Industrial Hemp Fiber Variety Trial. University of Vermont Extension. Retrieved from: https://www.uvm.edu/extension/nwcrops/research

Finnan J., Burke B. (2013). Potassium fertilization of hemp (Cannabis sativa). Industrial Crops and Products. 41:419-422.

Gauthier, N. Kentucky Hemp Diseases.  Management of Powdery Mildew Begins with Understanding the Causal Fungus. http://www.kyhempdisease.com/powdery-mildew-of-hemp.html

Hockey, J. F. 1927. Report of the Dominion field laboratory of plant pathology, Kentville, Nova Scotia.  Canada Department of Agriculture: 28-36.

Industrial Hemp Production and Management. Government of Manitoba, (2019). Web. Retrieved from: https://www.gov.mb.ca/agriculture/crops/production/hemp-production.html# 

Iványi and Izsáki, (2009). Effect of Nitrogen, Phosphorus, and Potassium Fertilization on Nutrional Status of Fiber Hemp. Communications in Soil Science and Plant Analysis. 40:974-986.

Kostuik, J., McEachern, S., Melnychenko, A. (2014). Hemp Fungicide Trial. Parkland Crop Diversification Foundation, Roblin, Manitoba.

Kryachko Z., M. Ignatenko, A. Markin and V. Zaets., 1965.  Notes on the hemp tortrix. Zashchita Rasteniî Vredit. Bolez. 5:51-54.

MacIndoo N.L.. and A.F. Sievers, (1924).  Plants tested for or reported to possess insecticidal properties. USDA Department Bulletin No. 1201. 61 pp.

McPartland, J. & Rhode, B. (2005). New Hemp Diseases and Pests in New Zealand, Journal of Industrial Hemp, 10:1, 99-108.

McPartland, J. M., (1996a).  A review of Cannabis diseases. Journal of the International Hemp Association 3(1): 19-23.

McPartland, J.M. (1996b). Cannabis pests. Journal of the International Hemp Association 3(2): 49, 52-55.

McPartland, J.M. (2000). Hemp Diseases and Pests: Management and Biological Control: an Advanced Treatise. CABI Publishing. Print.

Mushtaque M., G.M. Baloch and M.A. Ghani, (1973).  Natural enemies of Papaver spp. and Cannabis sativa. Annual report, Commonwealth Institute of Biological Control, Pakistan station, pp. 54-55.

Nair K.R. and K.M. Ponnappa, (1974).  Survey for natural enemies of Cannabis sativa and Papaver somniferum. Commonwealth Institute of Biological Control, India Station Report, pp 39-40.

Punja, Z. Cameron Scott, Sarah Chen. (2018) Root and crown rot pathogens causing wilt symptoms on field-grown marijuana (Cannabis sativa L.) plants. Canadian Journal of Plant Pathology 40:4, pages 528-541.

Roth, G. (2018). Industrial Hemp Trial Report. Pennsylvania State University Extension.

Stone, Dave. 2014. Cannabis, pesticides and conflicting laws: the dilemma for legalized States and implications for public health. Regulatory Toxicology and Pharmacology 69.3: 284-288.

Van der Werf, (1991). Agronomy and crop physiology of fibre hemp. A literature review. Center for Agrobiological Research (CABO-DLO), Wageningen, The Netherlands.

Van der Werf, H.M.G., & Van Geel W.C.A., (1994).  Vezelhennep als papiergrondstof, teeelton derzoek 1990-1993. [Fibre hemp as a raw material for paper, agronomic research 1990-1993.]  Report nr. 177, PAGV, Lelystad, The Netherlands.

Vera C.L., Malhi S.S, Phelps S.M., May W.E., Johnson E.N. (2010). N, P, and S fertilization effects on industrial hemp in Saskatchewan. Canadian Journal of Plant Science, 90:179-184.

Cooperators

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  • Sam Bellevance (Researcher)
  • Roger Rainville (Researcher)

Research

Materials and methods:

Objective 1. Develop optimum nitrogen rates for fertilizing industrial hemp in the Northeast.

Nitrogen rate studies were conducted in 2020 and 2021 to determine impact of nitrogen on yield and quality of hemp being grown for flower production. The project location in both years was Alburgh, VT. There were slight differences in materials because of product availability. As an example the nitrogen material applied in year one was sourced from a Canadian company that no longer carried the product. The product was liquid and used by many growers in our region. Unfortunately, we were unable to access the same product in 2021 and instead utilized a product available locally. The nitrogen rates were adjusted to include a higher rate in 2021 to see a more complete response curve. Lastly the variety differed again due to some seed availability and shipping issues experienced in 2021. As a result the results of the trials were analyzed and reported by year. Regardless, the nitrogen rate studies provided initial documentation of the impact that this nutrient can have on yield and quality of hemp from low to high rates.

Nitrogen Fertility Trial 2020

The trial was initiated at Borderview Research Farm in Alburgh, Vermont (Table 1) and the experimental design was a randomized complete block design with four replications. Plots consisted of five plants spaced 5’ apart in the row and plot treatments consisted of five N application rates including a Control (0 lbs ac-1), 75, 100, 125, and 150 lbs ac-1.

Table 1. Agronomic information for the hemp nitrogen fertility trial 2020. Alburgh, VT.

Location

Borderview Research Farm                        

 Alburgh, VT

Soil type

Benson rocky silt loam, 3-5% slope

Previous crop

Winter Canola

Plot size

5’ x 20’

Plant spacing (ft)

5’ x 5’

Variety

1 month old 'Lifter' seedlings

Planting date

9-Jun

Harvest date

8-Oct

Individual seeds were sown one seed per cell in Deep 50 cell plug trays on 5-May 2021. Supplemental lighting was provided during the day, and plants were given 18 hours of light.  Soil was watered to keep the soil surface sufficiently moist to effect germination and two fertilization applications were made with a low analysis 2-2-2 liquid fertilizer.

The 4-week-old hemp seedlings (variety Lifter) were transplanted on 9-Jun into a seed bed prepared with conventional tillage.  A cover crop mixture of crimson clover and annual ryegrass was planted between rows on 15-Jun. Drip irrigation was setup to supply moisture as needed by the hemp plants. Plots received nitrogen fertility in split applications over an eight-week period starting on 26-Jun in the form of ammonium nitrate plus sulfur (URAN 28-0-0) (Table 2).

 

Table 2. Weekly hemp nitrogen fertility rates (28-0-0).

Treatment

Application rate

 28-0-0

Weekly application rate

Weekly application rate

lbs ac-1

gal ac-1

gal ac-1

ml plant-1

0

0

0

0

75

23.1

2.89

6.27

100

30.8

3.85

8.36

125

38.5

4.81

10.5

150

46.1

5.77

12.5

Irrigation was applied on a weekly basis at a rate of 8000 gallons of water per acre delivered via drip tape. Irrigation duration and amount was modified based on weekly rainfall. Prior to harvest, plant height and width was measured from all harvested plants in each plot. From each plot, flower samples were taken from the top 8” of colas and were analyzed in UVM’s testing lab (Burlington, VT) for cannabinoid profiles.

For each plant harvested, the whole plant weight was recorded. On 8-Oct, all plants were harvested and were broken down into smaller branched sections and larger “fan” or “sun” leaves were removed by hand, while smaller leaves were left attached since they subtend from the flower bract. Remaining stems were then bucked using the BuckmasterPro Bucker (Maple Ridge, BC, Canada) and remaining leaf material and buds were collected. Wet bud and leaf material was then run through the CenturionPro Gladiator Trimmer (Maple Ridge, BC, Canada).  

Wet bud weight and unmarketable bud weight were recorded. The flower buds were then dried at 80⁰ F or ambient temperature with airflow until dry enough for storage without molding. A subsample of flower bud from each plot was dried in a small dehydrator and wet weights and dry weights were recorded in order to calculate the percent moisture of the flower buds. The percent moisture at harvest was used to calculate dry matter yields. Metrics were collected for each of the two harvested plants within each plot and a plot average was calculated.

The day prior to harvest (7-Oct) on plant per plot was harvested and chipped to be analyzed for whole plant nutrient concentrations. A subsample of chipped plants was taken, dried, and sent to Dairy One in Ithaca, NY for nutrient analysis.

 

Nitrogen Fertility Trial 2021

 The nitrogen fertility trial was repeated in 2021. The trial was conducted at the Borderview Farm in Alburgh, VT (UVM). Agronomic information for Alburgh, VT is provided in Tables 3. The experimental design was a randomized complete block design with five N rates (0-200 lbs/ac) and four replications.   The Alburgh site was disked and P and K were broadcast applied at 57 lbs of P2O5 and K2O/ac based on soil test results (Table 4).

 

Table 3.  Agronomic information for hemp nitrogen fertility trial, 2021.

Location

Borderview Research Farm – Alburgh VT

Soil type

Benson rocky silt loam soil   

Geographic coordinates

45.009080, -73.309259

Previous crop

Corn

Plot size

15 ft x 25 ft

Plant spacing

5 ft x 6 ft

Hemp variety

1 month old Elektra

   

Planting Date

June 2, 2021

Harvest Dates

September 21,22

 

Table 4.  Borderview soil test results, 2021.

Location

Borderview, Alburgh, VT

pH

6.5

Organic matter

4.8%

Phosphorus

6.8 lbs/ac

Potassium

116 lbs/ac

Calcium

4970 lbs/ac

Magnesium

222 lbs/ac

Individual seeds were sown one seed per cell in Deep 50 cell plug trays on 12 May 2021. Supplemental lighting was provided during the day, and plants were given 18 hours of light.  Soil was watered to keep the soil surface sufficiently moist to effect germination and two fertilization applications were made with a low analysis 2-2-2 liquid fertilizer.

At approximately four-weeks after sowing, hemp seedlings (variety Elektra) were hardened off and transplanted on 2-Jun in Alburgh.  Hemp plants were transplanted on a 5 x 5 spacing without black plastic.  The field was laid out and transplant locations were flagged out after the P and K had been applied and disked in.  Plants were soaked prior to transplanting to saturate the rooting medium and plants were placed in dug holes and watered in by hand. A cover crop mixture of crimson clover and annual ryegrass was planted between rows on 12-Jun. Drip irrigation was setup to supply moisture as needed by the hemp plants. 

Ammonium sulfate (21-0-0-24) was applied to each plot at 0, 50, 100, 150, and 200 lbs N/ac.  Gypsum was applied to balance the S in each treatment.  These applications were applied to the field in two applications, just prior to planting and three weeks later to avoid salt or fertilizer injury. Weeds were controlled through hand weeding through multiple passes taken on a bi-weekly basis during plant establishment. Irrigation was applied on a weekly basis at a rate of 8000 gallons of water per acre delivered via drip tape. Irrigation duration and amount was modified based on weekly rainfall. Prior to harvest, plant height and width was measured from all harvested plants in each plot. 

Pre-harvest, measurements for plant height and plant width were taken from middle three plants in each plot. For harvest measurements, two plants were cut at the base approximately 10 cm above the ground with loppers and the plant weight was recorded. An additional plant from each plot was harvested and run through a chipper shredder to determine whole plant dry matter and whole plant nutrient content.

Harvested plants were separated into individual branches and stripped of fan its fan leaves.  Flowers were separated from individual branches using a BuckmasterPro bucker (Maple Ridge, BC, Canada) in Vermont. In Vermont bucked flower was then fed through the CenturionPro Gladiator Trimmer (Maple Ridge, BC, Canada).  Wet bud weight and unmarketable bud weight were recorded. Stems were also collected and weighed.  Flower dry matter content was assessed by collecting a flower subsample and drying the flower sample overnight in a small dehydrator.  A subsample of flower was taken and analyzed in house at the E.E. Cummings Crop Testing Laboratory (Burlington, VT).  The percent moisture at harvest was used to calculate total dry matter and flower dry matter yields. Samples for whole plant nutrient analysis and leaf nitrogen measurements were sent to DairyOne Laboratories in (Ithaca, NY).

 

Objective 2. Identify viable biofungicides to control fungal diseases of hemp. Indications of success for farmers will include establishment of scouting protocols, management practices for diseases, and higher quality crops.

Disease Control Trial 2020 & 2021

Hemp research plots were established in spring of 2020 & 2021 at Borderview Farm in Alburgh, VT (45.0111° N, 73.3071° W). Two rows of 20 plants of ‘Boax’ cultivar  in 2020 and 'CBD White'  in 2021 on 10’ centers were used to compare two growing systems (low caterpillar and no covering) and evaluate four fungicides and a water control for foliage and bud disease incidence and severity. Four fungicides and one water control were applied to each hemp plant resulting in 20 treatment replications for each growing system. Five main branches encircling each plant, spread equidistantly were flagged. Of the flagged main branches, one vertical secondary shoot was selected 20 cm interior and was flagged for the fungicide treatment. Fungicides selected were based on those approved by the Vermont Agency of Agriculture Food and Markets for 2020 (Pesticide Use on Hemp in Vermont (6 VSA Chapter 87), VTAAFM DIVISION OF PUBLIC HEALTH AND AGRICULTURAL RESOURCE MANAGEMENT HEMP PROGRAM) with the exception of the Copper Hydroxide.   The following OMRI-approved fungicides and a water control were applied weekly starting at flower formation (9.13.20; 9.24.20; 9.29.20; 10.7.20; 10.15.20) through harvest (10.23.20)at standard label rates: Bacillus amyloliquefaciens (DoubleNickle LC, Certis Corp.); Hydrogen Peroxide and Peroxyacetic Acid (OxiDate; Biosafe Systems); Copper Hydroxide (Kocide 3000-O, Certis Corp.); Bacillus subtilis (Cease, Arbico Organics). All treatments received spreader sticker.

Treatment 1-Red-Kocide .56gr in 1000 mls X 3=1.68 gr/3 liters

Treatment 2-Green Oxidate 6.26 mls X 3= 18.78 mls/3 liters

Treatment 3-Pink-Double Nickel-1.56 ml in 1,000 mls= 4.68 mls/3 liters

Treatment 4-Orange-Cease Same as Double Nickel= 4.68 mls/3 liters

Treatment 5-Yellow-water

All applications were applied using a calibrated handheld sprayer to deliver 25 mls material/shoot. Foliage and bud disease incidence (number of leaves affected) and severity (area infected) were assessed at harvest by examining five leaves and five buds beginning at the terminal per vertical secondary shoot treatment in 2020.  In 2021, five leaves and ten buds beginning at the terminal per secondary shoot were examined. The Horsfall-Barratt scale (Horsfall and Barratt, 1945) was used to rate disease severity on foliage and buds. Diseases assessed included powdery mildew (Golovinomyces cichoracearum sensu lato/ https://doi.org/10.1094/PDIS-04-18-0586-PDN), fungal leafspot disease which was identified microscopically as septoria leaf spot (Septoria cannabis) and Botrytis bud blight (Botrytis cinerea). A subsample of foliage from the Kocide 3000 and Double Nickel treatments in both settings were collected for analysis of residues including copper.

On-Farm Trial with Sunset View Farm - 2020

Cover cropping has the potential to provide numerous benefits including nutrient retention, improvement of soil structure, weed suppression, and disease control. In 2020, an on-farm cover cropping trial was implemented to determine the impact of various cover crop species on hemp plant health, weed control, and fertility management.In the original project proposal we had proposed to conduct an experiment with a partner farm to evaluate biofungicides in a larger farm setting. Unfortunately, due to restrictions on some of the materials (labeled for research only) we were not able to conduct this research study with our partner farm. In collaboration with our partner farm we decided to investigate the role of cover crops seeded between the rows on pest and fertility management. Unfortunately, the soil conditions were extremely dry and the establishment rate was extremely poor. The farm had irrigation but it was under plastic mulch and only applied to the plants. We had planned to repeat the study in 2021, but the partner farm had to move locations and was in a state of transition.

The trial was implemented on 16-Jun at Sunset Lake CBD farm in Alburgh, VT. The experimental design was a randomized complete block with split plots and 4 replicates. The main plots were cover crop species mixtures (Table 5) and the split plots were seeding methods: broadcast and direct seeded. Plots were 5’x10’ planted between rows of Lifter hemp at Sunset Lake CBD. Plots that were direct seeded were planted at a rate of 10#/ac whereas broadcasted plots were planted at 20#/ac. Cover crop emergence was monitored in the week following planting and thereafter. 

Table 5. Cover crop treatments at Sunset Lake CBD Alburgh, VT 2020.

Treatment

Cover Crop

1

Control

2

Crimson clover

3

Balansa clover

4

Red clover

5

White clover

6

Berseem clover

7

Annual ryegrass

8

Crimson clover + annual ryegrass

9

Balansa clover + annual ryegrass

10

Red clover + annual ryegrass

11

White clover + annual ryegrass

12

Berseem clover + annual ryegrass

 

Objective 3. Qualify the species composition of arthropod and disease pest on industrial hemp on Vermont farms and quantify the impact of arthropod pests on industrial hemp.

A pest survey as conducted in 2020 and 2021 with partner farms throughout Vermont. There were 10 farms surveyed in 2020 and 11 farms surveyed in 2021. Eight of the farms were the same and three of the farms differed between years. 

Pest Survey 2020

Ten industrial hemp farms from throughout Vermont, representing eight different counties, were scouted. The farms enrolled the in the scouting program filled out a baseline production survey and provide their VT Hemp Registration Number. The ten farms were scouted for diseases and arthropod pests at two critical periods during the growing season; at flower development stage and just before harvest, since the type of diseases and pests will likely change over the course of the season. Three adjacent plants were scouted at five locations within each field in a W pattern to ensure all quadrants of the field are assessed. Five leaves were randomly selected including top, mid and lower sections on each of the three plants, as well as the terminal and 4 axillary cola buds, and evaluated for incidence (number of leaves affected) and severity (% total leaf damage) for each of the diseases and arthropod pests listed in the scouting form (See Disease and Arthropod Pest Scouting Forms). Stems, crown and root issues were also noted if present. When necessary, samples were collected and brought back to the UVM Plant Diagnostic laboratory for further diagnosis.

Pest Survey 2021

Eleven industrial hemp farms in Vermont were scouted, including two farms in Cornwall and Alburgh, and one farm in Hardwick, Stowe, Putney, Addison, and Morrisville, Hyde Park, and Wolcott. Since the type of diseases and pests will change over the course of the season, farms were scouted at two critical periods during the growing season: at flower development stage (mid-August) and just before harvest (mid- September). Three adjacent plants were scouted at five locations within each field in a W-shaped pattern to ensure all quadrants of the field were assessed. Five leaves were randomly selected including top, mid and lower sections of the plants, as well as the terminal and 4 axillary cola buds, and evaluated for incidence (number of leaves affected) and severity (% total leaf damage) for each of the diseases and arthropod pests listed in the scouting form. Incidence results refer to the leaves scouted, except for botrytis, which includes the cola buds. Stems, crown, and root issues were also noted if present, and the presence of other diseases, pests, or disorders was noted.

Research results and discussion:

Objective 1. Develop optimum nitrogen rates for fertilizing industrial hemp in the Northeast.

Nitrogen Fertility Trial 2020

Seasonal precipitation and temperature were recorded with a Davis Instrument Vantage Pro2 weather station, equipped with a WeatherLink data logger at Borderview Research Farm in Alburgh, VT (Table 6). The growing season was defined by hot and dry conditions throughout the summer months, punctuated by a handful of larger, infrequent rain events seen largely in August. June was especially dry during the transplant and establishment period for our hemp trials with below average precipitation in much of the growing season. Average temperatures during the growing period were 4.11 degrees higher than the 30-year average for the season with a 5.5% higher growing degree day accumulation for the year.

 Table 6. Seasonal weather data collected in Alburgh, VT, 2020.

Alburgh, VT

June

July

August

September

October

Average temperature (°F)

66.9

74.8

68.8

59.2

48.3

Departure from normal

1.08

4.17

0.01

-1.33

0.19

 

 

 

 

 

 

Precipitation (inches)

1.86

3.94

6.77

2.75

3.56

Departure from normal

-1.77

-0.28

2.86

-0.91

0.00

 

 

 

 

 

 

Growing Degree Days (Base 50°F)

516

751

584

336

126

Departure from normal

35

121

2

-24

-6

Based on weather data from a Davis Instruments Vantage Pro2 with WeatherLink data logger. Historical averages are for 30 years of NOAA data (1981-2010) from Burlington, VT.

 

Plant height did not differ significantly between N application rates (Table 7) with plants reaching an average of 157 cm tall. Whole plant weights were significantly different across treatments with plants receiving no supplemental nitrogen (control) and the 75 lbs N ac-1 rates having the lowest average plant weights compared to the top performer of 100 lbs N ac-1 at 16.5 lbs plant-1. The 150 and 125 lbs N ac-1 rates were statistically similar to the top performer, but weights were slightly lower at 15.8 and 15.0 lbs plant-1 respectively.

 

Table 7. Hemp whole plant weight, height, and width, Alburgh, VT, 2020.

Treatment

Plant height

Plant weight

lbs N ac-1

cm

lbs plant-1

Control

159

14.0

b

75

152

14.2

b

100

155

16.5

a

125

161

15.0

ab

150

155

15.8

ab

LSD (0.10)

NS¥

2.22

 

Trial Mean

157

15.1

 

†Within a column treatments marked with the same letter were statistically similar (p=0.10).

‡LSD – Least significant difference at p=0.10.

¥NS – No significant difference between treatments.

 

Total bud weight, leaf weight, and stem weight were measured at harvest to further evaluate growth characteristics of each nitrogen application rate (Table 8). In general, plants across treatments appeared to be fairly uniform in growth habit with little to no observable differences in appearance.  Across the trial, very few differences were apparent with only the bud weight of plants showing some treatment effect. Plants receiving the 100 lbs N ac-1 treatment had the highest overall average bud weight at 6.87 lbs plant-1 and were statistically similar to the 150 lbs N ac-1 treatment at 6.64 lbs plant-1. Other treatments yielded approximately 1 lb less per plant. With the Lifter cultivar in this trial, plants were on average 41.3% bud material, 25.2% stem, and 33.5% leaf. While leaf weights were not significantly different across treatments, the highest three rates of nitrogen did have the highest amount of leaf material within the trial, especially when comparing to the leaf weight of the control at 4.77 lbs plant-1. The amount of total leaf or stem material can influence a number of factors such as harvest time to remove excess leaf material for trimmed flower or harvestable plant material in a biomass production system. Amount of time required to harvest plants could vary drastically depending on desired end-product and intricacy of trimming, influenced largely by overall plant size and proportions of bud, leaf, and stem material.

 

Table 8. Hemp plant growth metrics, Alburgh, VT, 2020.

Treatment

Stem weight

Stem weight

Bud weight

Bud weight

Leaf weight

Leaf weight

Bud:stem

Leaf:stem

lbs N ac-1

lbs plant-1

% total

lbs plant-1

% total

lbs plant-1

% total

 

 

Control

3.40

24.6

5.84

b†

42.1

4.77

33.3

1.74

1.40

75

3.69

25.8

5.62

b

40.6

4.84

33.7

1.60

1.31

100

4.34

26.2

6.87

a

41.8

5.29

32.0

1.60

1.24

125

3.94

25.4

5.68

b

39.8

5.34

34.8

1.64

1.39

150

3.72

23.8

6.64

a

42.4

5.47

33.7

1.79

1.46

LSD (0.10)

NS¥

NS

0.667

 

NS

NS

NS

NS

NS

Trial Mean

3.82

25.2

6.13

 

41.3

5.14

33.5

1.67

1.36

†Within a column treatments marked with the same letter were statistically similar (p=0.10).

‡LSD – Least significant difference at p=0.10.

¥NS – No significant difference between treatments.

 

At harvest, a composite subsample of flower material was collected from each plot and dried down to determine flower dry matter and calculate dry matter flower yields (Table 9). Flower dry matter was not significantly different across treatments. Plants receiving the 100 lbs N ac-1 rate had the highest dry matter yields at 2884 lbs ac-1 alongside the 150 lbs N ac-1 rate at 2877 lbs ac-1. Those rates receiving additional fertility appeared to have the lowest amounts of unmarketable flower with the highest rate having on average 0.012 lbs plant-1 compared to the control which had the highest amount of unmarketable flower material. Unmarketable flower included any flower that had suffered from disease, rot, soil contamination, or otherwise damaged flower material. Dry matter flower yields for the Lifter cultivar within the trial averaged 2629 lbs ac-1 with an average flower dry matter of 24.7%.

Table 9. Hemp flower bud yield, Alburgh, VT, 2020.

Treatment

Flower dry matter

Unmarketable wet flower yield

Dry matter flower yield

lbs N ac-1

%

lbs plant-1

lbs ac-1

Control

25.4

0.072

b

2586

b†

75

24.4

0.038

ab

2389

b

100

24.1

0.016

ab

2884

a

125

24.4

0.050

ab

2407

b

150

25.0

0.012

a

2877

a

LSD (0.10)

NS¥

0.058

 

302

 

Trial Mean

24.7

0.037

 

2629

 

               

†Within a column treatments marked with the same letter were statistically similar (p=0.10).

‡LSD – Least significant difference at p=0.10.

¥NS – No significant difference between treatments.

€Dry matter yield is reported at 0% moisture.

 

Dried flower samples were also analyzed for CBD and THC concentrations and a CBD:THC ratio was calculated (Table 10). Results for cannabinoids are on a dry matter basis (0% moisture). Each of the analyzed cannabinoids, with the exception of D9-THC, showed statistically significant treatment responses to nitrogen fertility rates. For both CBDA and THCA, peak concentrations were observed in the 75 lbs N ac-1 treatment at 18.3% and 0.597% respectively, and was statistically similar to the Control, 100, and 125 lbs N ac-1 treatments. The CBD concentrations were again highest in the 75 lbs N ac-1 at 0.738% alongside similarly high values seen in the control at 0.602%. Highest values for total CBD were observed in the 75 lbs N ac-1 treatments at 16.8% and were statistically similar to the Control and 100 lbs N ac-1 treatments at 14.4% total CBD each. The 150 lbs N ac-1 treatment was consistently the lowest for all tested values for each analyzed cannabinoid and total cannabinoids resulting in a nearly 4% difference in total CBD. While the concentrations appeared to be impacted by nitrogen fertility rates, the ratio of CBD:THC was not impacted, remaining fairly consistent across all treatments. As concentrations of CBD increased or decreased for a given treatment, THC followed similar trends leading to proportionally similar cannabinoid concentrations for those analyzed.

 

Table 10. Hemp flower concentrations, Alburgh, VT, 2020.

Treatment

CBDA

CBD

D9-THC

THCA

Total THC

Total CBD ŧ

CBD : THC

 lbs N ac-1

%

%

%

%

%

%

%

Control

15.8

ab¥

0.602

ab

0.054

0.522

ab

0.512

ab

14.4

ab

28.2

75

18.3

a

0.738

a

0.071

0.597

a

0.594

a

16.8

a

28.3

100

15.7

ab

0.570

b

0.056

0.509

ab

0.503

ab

14.4

ab

28.5

125

15.2

ab

0.560

b

0.052

0.501

ab

0.492

ab

13.9

b

28.3

150

14.1

b

0.577

b

0.047

0.455

b

0.447

b

13.0

b

29.2

LSD (0.10)

3.16

 

0.145

 

NS ¥

0.102

 

0.110

 

2.88

 

NS

Trial mean

15.8

 

0.610

 

0.056

0.517

 

0.509

 

14.5

 

28.5

† Total potential CBD = (0.877 x CBDA) + CBD.

‡Total potential THC = (0.877 x THCA) + Δ-9 THC

¥Within a column treatments marked with the same letter were statistically similar (p=0.10).

€LSD – Least significant difference at p=0.10.

 ¥NS – No significant difference between treatments.

There were significant differences across treatments for concentrations of potassium, phosphorus, calcium, manganese, iron, and boron (Table 11). Highest values for potassium, phosphorus, and calcium were seen in the control at 1.94%, 0.635%, and 2.43% respectively. Potassium and phosphorus concentrations reacted similarly with statistically similar values observed in the 75 and 150 lbs N ac-1 treatments.  Lowest values for each of these three nutrients was seen at the 125 lbs N ac-1 treatment. Nitrogen management of soil is closely linked to the plant uptake of a wide number of nutrients. Differences in primary and secondary nutrient uptake can be influenced by a host of factors. Nitrogen applications can lead to decreases or increases in other nutrient utilization by the plant. Nitrogen applications can also acidify the soil depending on the source and rate of nitrogen applications. Lastly weather including excessive or limited precipitation can also influence nutrient availability. In the trial, regardless of nitrogen treatment the same amount of nitrogen was found in the plants. Other nutrient concentrations varied depending on the nitrogen rate; however there did not seem to be a clear relationship between the nitrogen treatment rates and concentrations of other nutrients accumulated in the hemp plants. Additional research across environments should be conducted to further evaluate the impact of nitrogen rates on uptake of other plant nutrients in hemp.

 

Table 11. Hemp whole plant nutrient analysis, Alburgh, VT, 2020.

Treatment

Nitrogen

Potassium

 

Phosphorus

 

Calcium

 

Magnesium

Carbon

 lbs N ac-1

%

%

 

%

 

%

 

%

%

Control

2.83

1.94

a†

0.635

a

2.43

a

0.281

17.7

75

2.81

1.79

ab

0.566

ab

2.36

ab

0.290

17.9

100

2.81

1.71

b

0.530

b

2.35

ab

0.273

17.8

125

2.78

1.70

b

0.507

b

2.19

b

0.272

18.1

150

2.74

1.79

ab

0.550

ab

2.26

ab

0.284

18.3

LSD (0.10)

NS

0.17

 

0.088

 

0.22

 

NS ¥

NS

Trial Mean

2.79

1.78

 

0.557

 

2.32

 

0.280

18.0

†Within a column treatments marked with the same letter were statistically similar (p=0.10).

LSD – Least significant difference at p=0.10.

¥NS – No significant difference between treatments.

 

Table 11 cont. Hemp whole plant nutrient analysis, Alburgh, VT, 2020.

Treatment

Manganese

 

Iron

 

Copper

Boron

 

Zinc

 lbs N ac-1

ppm

 

ppm

 

ppm

ppm

 

ppm

Control

64.8

b†

329

a

9.47

29.7

ab

40.0

75

63.3

b

269

b

8.58

27.3

a

36.4

100

86.3

a

300

ab

8.72

31.2

ab

38.3

125

67.5

b

303

ab

8.04

26.9

b

36.0

150

70.8

b

259

b

9.28

26.4

b

38.9

LSD (0.10)

13.6

 

53.9

 

NS ¥

4.03

 

NS

Trial Mean

70.5

 

292

 

8.82

28.3

 

37.9

†Within a column treatments marked with the same letter were statistically similar (p=0.10).

LSD – Least significant difference at p=0.10.

¥NS – No significant difference between treatments.

 

Nitrogen Fertility Results 2021

Seasonal precipitation and temperature were recorded with a Davis Instrument Vantage Pro2 weather station, equipped with a WeatherLink data logger at Borderview Research Farm in Alburgh, VT (Table 12). The growing season saw hot and dry periods through initial plant establishment. July was much cooler than normal. Overall dry conditions persisted throughout the summer months resulting in below average precipitation for the season. Average temperatures during the growing period were 5.97 degrees higher than the 30-year average for the season with a 4.69% higher growing degree day accumulation for the year.

Table 12. Seasonal weather data collected in Alburgh, VT, 2021.

Alburgh, VT

June

July

August

Sept

Oct

Average temperature (°F)

70.3

68.1

74.0

62.8

54.4

Departure from normal

2.81

-4.31

3.25

0.14

4.07

 

 

 

 

 

 

Precipitation (inches)

3.06

2.92

2.29

4.09

6.23

Departure from normal

-1.20

-1.14

-1.25

0.42

2.40

 

 

 

 

 

 

Growing Degree Days (50-86°F)

597

561

727

394

217

Departure from normal

73

-134

85

7

79

Historical averages are for 30 years of data provided by the NOAA (1991-2020) for Burlington, VT.

   

 

Plants heights differed between treatments with the highest observed values seen in the 100 lbs N ac-1 rate at 182 cm and was statistically similar to the 200 lbs N ac-1 treatment and the control, with an average trial height of 166 cm (Table 13). No significant differences were observed in plant width or whole plant weight at harvest, but plants within the trial averaged 165 cm in width and 19.8 lbs plant-1.

 

Table 13. Hemp whole plant weight, height, and width, Alburgh, VT, 2021.

Treatment

Plant height

Plant width

Plant weight

lbs N ac-1

cm

cm

lbs plant-1

0

165a

169

18.3

50

151b

152

19.8

100

182a

176

20.2

150

153b

154

19.7

200

179ab

174

20.8

LSD (0.10)

28.1

NS¥

NS

Trial Mean

166

165

19.8

†Within a column, treatments with the same letter are not significantly different from each other.

‡LSD – Least significant difference at p=0.10.

¥NS – No significant difference between treatments.

 

Total bud weight, leaf weight, and stem weight were measured at harvest to further evaluate growth characteristics of plants from each nitrogen application rate (Table 14). In general, plants across treatments appeared to be uniform in growth habit with little to no observable differences in appearance. Across the trial, very few differences were apparent when looking at the weights of the fractional components with no significant differences observed in stem weight, bud weight, or leaf weight. When looking at the component in terms of percentage of total plant weight or proportions in relation to one another, some differences emerged in stem weight and leaf weight percentages. This highest total percentage of stem was seen in the 200 lbs N ac-1 treatment at 36.9% and was statistically similar to all but the 50 lbs N ac-1 treatment. Conversely, the 200 lbs N ac-1 treatment had the lowest percentage of leaf material at 26.5%. highest leaf proportions were seen in the 100 lbs N ac-1 treatment at 33.9%. The amount of total leaf or stem material can influence a number of factors such as harvest time to remove excess leaf material for trimmed flower or harvestable plant material in a biomass production system. Amount of time required to harvest plants could vary drastically depending on desired end-product and intricacy of trimming, influenced largely by overall plant size and proportions of bud, leaf, and stem material. While not statistically significant, the average bud weight for the control treatments were lower than all other treatments at 6.37 lbs plant-1 with other treatments ranging from 7.06-8.17 lbs plant-1.

Table 14. Hemp plant growth metrics, Alburgh, VT, 2021.

Treatment

Stem weight

Stem weight

Bud weight

Bud weight

Leaf weight

Leaf weight

Bud:stem

Leaf:stem

lbs N ac-1

lbs plant-1

% total

lbs plant-1

% total

lbs plant-1

% total

 

 

0

6.28

33.8ab

6.37

35.6

5.67

30.7ab

1.09

0.910ab

50

6.04

30.5b

8.17

41.1

5.61

28.5ab

1.35

0.940ab

100

6.32

31.3ab

7.06

34.8

6.85

33.9a

1.22

1.18a

150

6.03

31.0ab

7.62

38.0

6.03

31.0ab

1.25

1.01ab

200

7.58

36.9a†

7.61

36.6

5.63

26.5b

1.02

0.750b

LSD (0.10)

NS¥

6.06

NS

NS

NS

5.93

NS

0.332

Trial Mean

6.45

32.69

7.37

37.2

5.96

30.1

1.19

0.96

†Within a column, treatments with the same letter are not significantly different from each other.

‡LSD – Least significant difference at p=0.10.

¥NS – No significant difference between treatments.

 

At harvest, a composite subsample of flower material was collected from each plot and dried down to determine flower dry matter and calculate dry matter flower yields (Table 15). Flower dry matter was not significantly different across treatments and there were no significant differences in yields across nitrogen fertility treatments within this trial. Unmarketable flower included any flower that had suffered from disease, rot, soil contamination, or otherwise damaged flower material.

Table 15. Hemp flower bud yield, Alburgh, VT, 2021.

Treatment

Flower dry matter

Unmarketable wet flower yield

Dry matter flower yield

lbs N ac-1

%

lbs plant-1

lbs ac-1

0

21.2

73.3

2387

50

21.8

66.2

3081

100

21.5

82.6

2625

150

19.5

90.9

2525

200

20.1

51.8

2622

LSD (0.10)

NS¥

NS

NS

Trial Mean

20.8

72.9

2648

‡LSD – Least significant difference at p=0.10.

¥NS – No significant difference between treatments.

Dry matter yield is reported at 0% moisture.

 

Whole plants were chipped and analyzed for primary and secondary plant nutrients (Table 16). There were significant differences across treatments for concentrations of nitrogen, phosphorus, calcium, sulfur, carbon, iron, and zinc.  Highest values for nitrogen, calcium and sulfur were observed in the 150 lbs N ac-1 treatment at 2.96%, 2.19%, and 0.280% respectively. Lowest concentrations for many of these nutrients were observed in the 50 lbs N ac-1 treatment with the exception of iron which showed the highest concentrations for the treatment at 831 ppm. Nitrogen management of soil is closely linked to the plant uptake of a wide number of nutrients. Nitrogen applications can lead to decreases or increases in other nutrient utilization by the plant. Nitrogen applications can also acidify the soil depending on the source and rate of nitrogen applications. Lastly weather including excessive or limited precipitation can also influence nutrient availability. There did not seem to be a clear relationship between the nitrogen treatment rates and concentrations of other nutrients accumulated in the hemp plants. Additional research across environments should be conducted to further evaluate the impact of nitrogen rates on uptake of other plant nutrients in hemp.

 

Table 16. Hemp whole plant nutrient analysis, Alburgh, VT, 2021.

Treatment

Nitrogen

Potassium

Phosphorus

Calcium

Magnesium

Sulfur

Carbon

 lbs N ac-1

%

%

%

%

%

%

%

0

2.81a

1.69

0.370a

2.02ab

0.304

0.265a

16.8ab

50

2.36b

1.56

0.279b

1.74b

0.265

0.205b

19.8a

100

2.38b

1.63

0.346ab

1.87ab

0.263

0.225b

19.8a

150

2.96a

1.80

0.365ab

2.19a

0.261

0.280a

16.0b

200

2.7ab

1.68

0.327ab

1.82ab

0.264

0.250a

17.5ab

LSD (0.10)

0.398

NS¥

0.091

0.42

NS

0.051

3.02

Trial Mean

2.64

1.67

0.337

1.93

0.271

0.245

18.0

†Within a column, treatments with the same letter are not significantly different from each other.

‡LSD – Least significant difference at p=0.10.

¥NS – No significant difference between treatments.

 

Table 16 cont. Hemp whole plant nutrient analysis, Alburgh, VT, 2021.

Treatment

Manganese

Iron

Copper

Boron

Zinc

 lbs N ac-1

ppm

ppm

ppm

ppm

ppm

0

129

540b

17.0

32.0

47.3ab

50

116

831a

12.6

26.6

41.0b

100

142

492b

13.5

27.1

43.2ab

150

168

551b

15.9

30.4

55.4a

200

185

393b

16.0

26.3

46.5ab

LSD (0.10)

NS¥

206

NS

NS

10.8

Trial Mean

148

562

15.0

28.5

46.7

†Within a column, treatments with the same letter are not significantly different from each other.

‡LSD – Least significant difference at p=0.10.

¥NS – No significant difference between treatments.

 

Dried flower samples were also analyzed for CBD and THC concentrations (Table 17). Results for cannabinoids are on a dry matter basis (0% moisture). Each of the analyzed cannabinoids showed no significant differences across treatments throughout the study with a trial average for total potential THC reaching 0.494% and a total potential CBD concentration reaching 11.9%.

Table 17. Hemp flower cannabinoid concentrations. Alburgh, VT, 2021.

Treatment

D9-THC

CBD

THCa

CBDa

Total potential THC

Total potential CBD

Total cannabinoids

 

%

%

%

%

%

%

%

0

0.047

0.452

0.478

12.3

0.466

11.2

13.9

50

0.153

0.452

0.508

13.2

0.497

12.0

14.7

100

0.054

0.486

0.533

13.8

0.522

12.6

15.5

150

0.049

0.478

0.476

12.5

0.467

11.4

14.1

200

0.138

0.445

0.537

13.4

0.517

12.2

15.1

LSD (0.10) ¥

NS

NS

NS

NS

NS

NS

NS

Trial Mean

0.088

0.462

0.506

13.0

0.494

11.9

14.6

† Total potential CBD = (0.877 x CBDA) + CBD.
‡Total potential THC = (0.877 x THCA) + Δ-9 THC.

¥LSD – Least significant difference at p=0.10.

€NS – No significant difference between treatments.

 On-Farm Trial 2020

Cover crop establishment was slow and poor due to low precipitation following planting. Cover crops that emerged were quickly outcompeted by warm season weed species primarily including pigweed and barnyard grass as the months of June and July offered little to no precipitation and higher than average temperatures. As a result, impact of cover crop treatments was not able to be evaluated past this point due to poor establishment as they were outcompeted by high weed pressure. Despite multiple efforts to knock back weeds through mowing and weed whacking, plots were not able to establish. The overall lack of moisture in June, with precipitation nearly 2 inches below average, led to exceptionally slow germination of the cover crops and in some cases patchy to non-existent stands.   While cover crops did not have the ability to outcompete weeds in this instance, ground cover in the form of those weed species remained. Through side by side observation, there may have been some apparent impact of ground cover on disease pressure from Septoria leaf spot. Adjacent rows to this trial appeared to have heavy pressure from the soil borne disease whereas rows with vegetation in between plantings had lesser observable disease. While individual cover crop impacts were not able to be evaluated, there may be additional benefits of disease control from ground cover that would reduce splash up of soil bone diseases. Additional evaluation in future years would be required to determine this impact.

 

Objective 2. Identify viable biofungicides to control fungal diseases of hemp. Indications of success for farmers will include establishment of scouting protocols, management practices for diseases, and higher quality crops.

Disease Control Trial 2020

9.13.30- No disease found on field plants foliage or buds. Powdery mildew rated at 50% in the tunnel. No insect injury on inside or outside. Darby and Hazelrigg.

9.24.20- No disease found on field plants foliage or buds. Powdery mildew rated at 50% in the tunnel. No insect injury on inside or outside. Hazelrigg and Bruce.

9.29.20- No disease found on field plants foliage or buds. Powdery mildew rated at 50% in the tunnel. No insect injury on inside or outside. Darby.

10.7.20- No disease found on field plants foliage or buds. Powdery mildew rated at 50% in the tunnel. No insect injury on inside or outside. Darby.

10.16.20- Some abiotic injury in outdoor plants (pictures above). Bud rot as follows:

  • Terminal bud rot on red on 5th plant in from FIELD. Kocide
  • Terminal bud rot on 3rd green in from ROAD-Oxidate
  • Terminal bud rot on 4th yellow in from ROAD- Water
  • Terminal bud rot on red 5th plant from the ROAD-Kocide

Powdery mildew rated at 50% in the tunnel, 25% outside. No bud rot inside tunnel.  No insect injury on inside or outside.

10.23.20-All flagged shoots were collected and the first terminal down 5 buds were assessed for incidence and severity of bud rot caused by Botrytis. Statistical analysis indicated that there were no differences between the treatments for incidence or severity of flower rot. The project did indicate that hemp grown under cover (low tunnels) had less flower rot but overall the incidence of rot was low for the entire project.

In the low tunnel there was very low infection rate with only 6/490 buds showing symptoms of rotting flower (1.225% incidence).

  • Kocide Trt 1                 0 buds/95 bud infected
  • Oxidate Trt 2                0 buds/95 buds infected
  • Double Nickel Trt 3       2 buds/100 buds infected. S=2@75%
  • Cease Trt 4                  1 bud/100 buds infected. S= 1@100%
  • Water Trt 5                3 buds/100 buds infected. S=2@25%,1@100%

In the field the total number of flower buds showing symptoms of rotting flowers was higher but still low overall. The total buds infected       was 40/485 buds (8.247% incidence).

  • Kocide Trt 1                  6/100 buds infected. S= 6@100%         
  • Oxidate Trt 2                8/95 buds infected. S=6@100%,1@25%,1@50%
  • Double Nickel Trt 3        7/95 buds infected. S-5@100%,1@ 50%, 1@25%
  • Cease Trt 4                  7/95 buds infected. S=6@ 100%, 1@25%
  • Water Trt 5                 12/100 buds infected. S=10 @100%, 2@50%

A subsample of the Kocide and Double Nickel treatments, low tunnel and field hemp flowers were collected for analysis of copper and microbial residues. There is concern that application of biological materials as well as copper can keep farmers from meeting regulatory standards for these quality measurements. Regulatory standards are looking at thresholds for aerobic plate counts and yeast/mold counts from  flower samples. Addition of a biological fungicide (Double Nickel) did increase the aerobic microbial count and yeast/mold counts compared to the control.  Copper based fungicides (even those applied outdoors) substantially increased the copper concentration of the harvested flower buds. Further research needs to be conducted to understand market and safety concerns of the hemp products.

RESULTS Copper and Microbial Analysis

Treatment                                Copper Content  ppb          Aerobic count cfu/g     Yeast/Mold count cfu/g

 Inside Double Nickel                16885                                            33,350                             13,050

Outside Double Nickel              12493                                             6,164                             27,562

Inside Kocide                           408135                                              92                             12,375

Outside Kocide                        143025                                            184                               5,400

Inside Control                            14508                                            92                                6,525

Outside Control                          15765                                             0                                 3,600

 

Disease Control Trial 2021

In Year 2, there was minimal powdery mildew identified in the Low Tunnel site and was rated as overall infection of less than 5%. There was no powdery mildew detected under Field conditions. Although both sites showed incidence of Botrytis bud rot, there was no significant difference among fungicide treatments in either site or in incidence of bud rot between sites. There was no difference in Septoria leafspot incidence among fungicide treatments in the Low Tunnel yet under Field conditions, Septoria incidence was significantly less in the Kocide 3000 treatment compared with any other treatment Table 18. Powdery mildew was present in both sites but there was significant differences in fungicide treatments only in the Low Tunnel with Kocide 3000 controlling the disease significantly better than the other treatments with the exception of Oxidate (Table 19). 

Table 18. Comparison of fungicides on the incidence of septoria leaf spot in the Field in Year 2.

 

Fungicide

Disease incidence

 

 

Cease

0.4433

a†

 

Water

0.4367

a

 

Oxidate

0.43

a

 

Double Nickel

0.3933

a

 

Kocide

0.0667

†Fungicides with the same letter did not perform statistically different from each other (p=0.10)

Table 19. Comparison of fungicides on the incidence of powdery mildew in the Low Tunnel in Year 2.

 

Fungicide

Disease incidence

 

 

Water

0.64

a†

 

Double Nickel

0.3767

  b

 

Cease

0.2933

  b

 

Oxidate

0.1467

  bc

 

Kocide

0.0667

    c

†Fungicides with the same letter did not perform statistically different from each other (p=0.10)

 

 On-Farm Trial 2020

Cover crop establishment was slow and poor due to low precipitation following planting. Cover crops that emerged were quickly outcompeted by warm season weed species primarily including pigweed and barnyard grass as the months of June and July offered little to no precipitation and higher than average temperatures. As a result, impact of cover crop treatments was not able to be evaluated past this point due to poor establishment as they were outcompeted by high weed pressure. Despite multiple efforts to knock back weeds through mowing and weed whacking, plots were not able to establish. The overall lack of moisture in June, with precipitation nearly 2 inches below average, led to exceptionally slow germination of the cover crops and in some cases patchy to non-existent stands.   While cover crops did not have the ability to outcompete weeds in this instance, ground cover in the form of those weed species remained. Through side by side observation, there may have been some apparent impact of ground cover on disease pressure from Septoria leaf spot. Adjacent rows to this trial appeared to have heavy pressure from the soil borne disease whereas rows with vegetation in between plantings had lesser observable disease. While individual cover crop impacts were not able to be evaluated, there may be additional benefits of disease control from ground cover that would reduce splash up of soil bone diseases. Additional evaluation in future years would be required to determine this impact.

Objective 3. Qualify the species composition of arthropod and disease pest on industrial hemp on Vermont farms and quantify the impact of arthropod pests on industrial hemp.

Pest Survey 2020

Leaf spots (overwhelmingly Septoria) were the most widespread disease found during flower development in Vermont, observed at half of the scouting locations (Table 20). Of the two locations where powdery mildew was seen during flowering, Alburgh-1 and Berlin, there was a relatively large number of leaves effected, 40% and 53.3%, respectively. Just prior to harvest, the incidence of powdery mildew increased such that it was seen at half of the locations, and as much as half of the scouted leaves at Alburgh-1 had powdery mildew. Leaf spots were also common, found at four of the ten locations, but only at Alburgh-2 was it severe – 77.3% of the scouted leaves had leaf spots.  Botrytis was present at relatively low levels (1-3% of the scouted buds showed signs of Botrytis) at three of the ten farms. Some of the other diseases that were found at very low levels included Bipolaris leaf spots, Sclerotina stem rot, and powdery mildew affected flowers.

During flower development, six out of ten of the farms had flea beetles, up to 0.6/leaf (Table 21). Aphids and potato leafhoppers were present at relatively low numbers at some of the locations for that time-period. As the season progressed, aphid numbers predictably rose across most locations, though three out of ten farms didn’t have any aphids present when scouted prior to harvest.  On the seven farms where aphids were found pre-harvest, Berlin and Morrisville saw the greatest numbers, 1.91/leaf and 1.72/leaf, respectively. There were virtually no other insects found during that later scouting. A fair amount of feeding damage was seen at many locations throughout the season, we largely attribute the observed damage to flea beetles and plant bugs.

Table 20. The incidence (number of effected plants/total number of plants scouted) and average severity (percent of leaf/bud effected) of diseases commonly found on hemp plants, during two scouting periods, at Vermont hemp farms in 2020. 

    Flowering Pre-harvest
    Leaf spots Powdery Mildew Leaf spots Powdery Mildew Botrytis
Location Varieties Inc (%) Sev (%) Inc (%) Sev (%) Inc (%) Sev (%) Inc (%) Sev (%) Inc (%) Sev (%)
Addison Cat's Meow 0 0 0 0 0 0 0 0 0 0
Alburgh-1 Boax 0 0 53.3 20.6 0 0 52.0 16.3 0 0
Alburgh-2 White CBG 1.3 12.9 0 0 77.3 22.8 45.3 9.7 0 0
Berlin Honolulu Haze, Suver Haze, Green Mountain Cherry 0 0 40.0 10.3 4.0 0.5 26.7 4.0 0 0
Colchester White 17.3 1.7 0 0 0 0 0 0 0 0
Craftsbury Lifter 29.3 0 0 0 20.0 3.9 2.7 0.3 2.7 3.6
Morrisville Suvar Haze 25.3 2.7 0 0 23.0 2.9 0 0 3.0 0.8
Pittsfield Lifter 0 0 0 0 0 0 0 0 0 0
Putney Lifter, Electra, CBG, Suver Haze 0 0 0 0 0 0 21.3 2.1 1.3 1.3
Williston Suver Haze, Special Sauce, White CBG 9.3 0.2 0 0 0 0 0 0 0 0

Table 21. Average number of individuals/leaf found on hemp plants, during two scouting periods, at Vermont hemp farms in 2020.

    Flowering Pre-harvest
Location Varieties Aphids Flea Beetles Leafhoppers Aphids Flea Beetles Potato Leafhoppers
Addison Cat's Meow 0.03 0.03 0.01 0.59 0 0
Alburgh-1 Boax 0 0 0 0.40 0.01 0
Alburgh-2 White CBG 0.37 0.09 0 0.16 0 0
Berlin Honolulu Haze, Suver Haze, Green Mountain Cherry 0.03 0 0 1.91 0 0
Colchester White 0 0.09 0 0 0 0
Craftsbury Lifter 0 0 0 0.09 0 0
Morrisville Suvar Haze 0.03 0 0.01 1.72 0 0
Pittsfield Lifter 0.15 0.19 0.00 1.07 0 0
Putney Lifter, Electra, CBG, Suver Haze 0 0.29 0 0 0 0
Williston Suver Haze, Special Sauce, White CBG 0 0.60 0 0 0 0

 

Pest Survey 2021

Survey information is still being processed and analyzed. Preliminary data suggests leaf spots were the only disease that was prevalent on hemp throughout VT in 2021, while powdery mildew occurred sporadically in some locations. Other than that, disease pressure was relatively low. Hemp aphid pressure was uncharacteristically low in 2021, while potato leafhopper, flea beetles, and European corn borer were also present throughout the state, also in relatively low numbers.

Diseases Identified On-Farm:

The warm and dry growing conditions throughout much of the season resulted in relatively low levels of foliar and root disease. Sclerotinia white mold and powdery mildew was observed on farms throughout VT. Leaf spots were seen at every farm site except one farm in Addison, Vermont. Botrytis was also recorded on every farm. Data by scouting date and farm are shown in Tables 22.

Table 22. The average severity of diseases on hemp at flowering and pre-harvest in Vermont, 2021. Severity is for 5 leaves per plant on 15 plants per field.

 

Flowering

Pre-harvest

Town

Leaf spots

Powdery Mildew

Botrytis

Sclerotinia

Leaf spots

Powdery Mildew

Botrytis

Sclerotinia

 

Sev (%)

Sev (%)

Sev (%)

Sev (%)

Sev (%)

Sev (%)

Sev (%)

Sev (%)

Alburgh- Borderview

0.467

0.0

0.0

0.0

21.5

3.07

0.0

2.40

Cornwall

0.0

0.0

0.0

0.0

4.87

0.0

0.067

0.0

Cornwall Site 2

0.0

0.0

0.0

0.0

0.07

7.33

3.60

0.0

Alburgh Site 2

4.07

0.0

0.0

0.0

10.13

0.0

3.60

1.60

Addison

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

Hardwick

6.27

0.0

0.0

0.0

23.7

0.0

0.0

0.0

Stowe

19.1

0.0

0.0

0.0

0.0

18.1

0.0

0.267

Morrisville

19.1

0.0

0.0

0.0

4.67

0.0

0.88

0.0

Hyde Park

8.53

0.0

0.0

0.0

6.40

1.73

0.0

0.267

Wolcott

0.0

0.0

0.0

0.0

1.20

0.0

0.0

0.0

Putney

0.0

0.0

0.0

0.0

8.50

0.0

3.58

0.0

 

Arthropod Pests Identified On-Farm

 Spider mites and thrips were the least common pests seen on the hemp leaves. Thrips, European cornborers (ECB) and flea beetles were observed sporadically on farms. Aphids were the primary insect pests followed by leaf hoppers. Scouting data by date, location, and species are shown in Table 23.

 

Table 23. Average number of arthropods per leaf during two scouting periods, Vermont, 2021. Incidence is for 5 leaves per plant on 15 plants per field.

 

Flowering

 

Pre-harvest

 

Town

Aphids

ECB

Spider Mites

Flea Beetle

Potato Leafhopper

Thrips

Aphids

ECB

Spider Mites

Flea Beetle

Potato Leafhopper

Thrips

Inc

Inc

Inc

Inc

Inc

Inc

Inc

Inc

Inc

Inc

Inc

Inc

Alburgh- Borderview

1.32

0.0

0.0

0.0

0.027

0.0

7.17

0.027

0.0

0.0

0.947

0.0

Alburgh 2

0.027

0.04

0.0

0.107

0.0

0.0

0.413

0.04

0.0

0.0

0.0

0.0

Cornwall 1

0.0

0.0

0.0

0.0267

0.013

0.08

0.36

0.0

0.0

0.0

0.0

0.0

Cornwall 2

0.0

0.0

0.0

0.0

0.0

0.0

0.707

0.0

0.0

0.0

0.0

0.0

Addison

0.413

0.013

0.0

0.027

0.093

0.0

0.84

0.027

0.0

0.0

0.0

0.0

Hardwick

2.65

0.0

0.0

0.0

0.0

0.0

0.107

0.0

0.0

0.0

0.013

0.0

Stowe

0.08

0.0

0.0

0.0

0.053

0.0

0.0

0.0

0.0

0.0

0.0

0.0

Morrisville

0.04

0.0

0.0

0.04

0.027

0.0

0.133

0.0

0.0

0.0

0.0

0.0

Hyde Park

1.04

0.0

0.0

0.013

0.0

0.0

1.63

0.0

0.0

0.0

0.013

0.0

Wolcott

0.507

0.0

0.0

0.0

0.013

0.0

0.173

0.0

0.0

0.0

0.013

0.0

Putney

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

                               

 

 

Research conclusions:

Nitrogen Fertility and Hemp

As we continue to investigate nitrogen response in high cannabinoid hemp, some similarities can be observed between past research done in grain and fiber, however through two years of study in flower hemp, there appears to be greater variability in nitrogen uptake for flower production. Some grain and fiber hemp research have shown that the majority of nitrogen uptake occurs during the first month of growth during vegetative periods. This ends up being a critical growth period for high cannabinoid hemp as well with the rapid uptake of nitrogen occurring during the vegetative production period. Additionally, a positive yield and biomass response in grain and fiber varieties is seen with increased nitrogen application rates up to approximately 130 lbs N ac-1. Past this point, additional nitrogen appears to have no major impact on growth.

In 2020 & 2021 nitrogen rates from 0 to 200 lbs of N per acre were applied to hemp being grown for flower production. In 2020, total plant weight increased as nitrogen rates increased. However there was no clear response in dry matter flower yields to the nitrogen rates. It was not clear as to what minimum rate would lead to a yield response. There was more unmarketable yields in the control treatment in 2020 compared to other higher nitrogen rates. The percentage of nitrogen in the whole plant biomass did not differ between treatments although there were some differences in uptake of other plant nutrients. There was some evidence in 2020 that CBD and THC concentrations were suppressed with increasing application rates of nitrogen.  However, in 2021 increasing rates of nitrogen did not lead to higher plant weights. The nitrogen concentrations of the whole plant did differ by rate but highest percentages of nitrogen when were found in the 0, 150, and 200 lb of N per acre treatments. Similar to 2020, dry matter flower yield did not show a consistent response to increasing rates of nitrogen fertility. Also in 2021, the CBD and THC concentrations did not show a response to increasing rates of nitrogen.  The weather conditions were extremely dry in 2021 and may have influence the availability of nitrogen to the hemp plants. Losses of nitrogen are often far greater in normal years. The lack of rainfall and hot temperatures may have provided ample nitrogen in all treatments. Background fertility from past year crops and fertility amendments may have played a role in the lack of treatment differences in these trials. An adaptive nitrogen management tool such as a PreSidedress Nitrogen Test may be an important tool for hemp growers. This type of test would allow a grower to understand nitrate-N available from past year soil amendments and organic matter.

Hemp Fungicide Trials

Fungal diseases were documented in the pest survey as being prevalent throughout farms in the northeast.  Farmers need a tool box of management options to control these potentially yield and quality devastating diseases. Through this project, 4 biological and organic approved fungicides were evaluated for control of fungal diseases in the hemp. Hemp grown in protective structures had less overall disease compared to hemp plants grown outside. This is a similar observation to other vegetable crops grown in high tunnels that tend to yield higher and are less prone to losses from disease and other abiotic/biotic stresses. Dry conditions in both 2020 and 2021 resulted in low incidence of disease.  In 2021, there was more disease observed in the trial, especially high levels of Septoria leafspot. There was no difference in Septoria leafspot incidence among fungicide treatments in the Low Tunnel yet under Field conditions, Septoria incidence was significantly less in the Kocide 3000 treatment compared with any other treatment. Powdery mildew was present in both sites but there was significant differences in fungicide treatments only in the Low Tunnel with Kocide 3000 controlling the disease significantly better than the other treatments with the exception of Oxidate.  Overall, copper based treatments (Kocide 3000) were the only organic approved treatment that show efficacy. Unfortunately application of copper-based products also led to substantially higher levels of copper accumulation in the flower buds. This could potentially lead to rejection in the market place. It will also be important to continue to evaluate the impact that biologically based fungicides have on yeasts, molds, and aerobic bacterial counts as thresholds of these tests may become part of regulatory frameworks. Additional research is needed to help farmers develop viable IPM strategies to combat diseases in hemp.

Hemp Pest Survey

In 2020 and 2021, hemp pests were evaluated on a total of 13 farms throughout Vermont. Since the type of diseases and pests change over the course of the season, farms were scouted at two critical periods during the growing season; at flower development stage (mid-August) and just before harvest (mid-September). Leaf spots (overwhelmingly Septoria) and Botrytis were the most widespread disease found throughout the region. Powdery mildew was also observed but not at every location. Seen during flowering, Alburgh-1 and Berlin, there was a relatively large number of leaves effected, 40% and 53.3%, respectively. Some of the other disease that were found at very low levels included Bipolaris leaf spots, Sclerotina stem rot, and powdery mildew. In regards to arthropods, aphids and potato leafhoppers were present at relatively low numbers at all locations. As the season progressed, aphid numbers predictably rose across most farms. Overall arthropod incidence and damage was low throughout Vermont. Since hemp has been grown a relatively short time in the region we expect over time that the incidence and severity of diseases will likely increase. Proper rotations and other cultural practices will be central to disease management for hemp.

Participation Summary
13 Farmers participating in research

Education & Outreach Activities and Participation Summary

45 Consultations
6 Curricula, factsheets or educational tools
1 On-farm demonstrations
7 Published press articles, newsletters
10 Webinars / talks / presentations
2 Workshop field days
2 Other educational activities: The 2nd Annual UVM Industrial Hemp Conference - 2020
The 3rd Annual UVM Industrial Hemp Conference - 2021

Participation Summary:

540 Farmers
419 Number of agricultural educator or service providers reached through education and outreach activities
Education/outreach description:

The 2nd Annual Hemp Conference was held on February, 2020 in Burlington, VT. There were 375 attendees from 10 states and 2 provinces. An online version of the conference was also held in conjunction. There presentations focused on pest and fertility management with UVM research projects highlighted. Hemp Conference Brochure - 2020

The 3rd Annual Hemp Conference was held virtually in February, 2021. There were 185 attendees from 8 states and 3 provinces. The conference provided information on pest and fertility management, variety selection, marketing, and a wide range of diverse hemp information. Research from the SARE trials was highlighted. There were 16 live presentations and 13 on-demand presentations. Essentially there was nearly 25 hours of educational material offered through the conference. The presentations were all recorded and were made available to participants. This allowed attendees to learn after the conference. Hemp Conference Brochure -2021

In the spring of 2020, a webinar series focused on hemp was delivered to stakeholders during the summer of 2020. There were 7 webinars held from June through September. The goal was to provide timely information to growers related to production and regulation. 

Hemp Webinars, Jun 11, 18, Jul 7, 30, Aug 6, 13, Sep 10, 2020, Information for growing hemp throughout the season, 7 webinar series, virtual event, 294 attendees, https://www.uvm.edu/extension/nwcrops/conferences-events-current-and-past 

Individual webinars are listed below with links to archived webinars.

The Vermont Hemp Rules with Stephanie Smith (11 Jun 2020) 212 views https://www.youtube.com/watch?v=Z02EyQkkN9U&feature=youtu.be 

Getting the Season Started with Heather Darby and John Bruce of the UVM Extension Northwest Crops and Soils Program (18 Jun 2020) 62 views https://www.youtube.com/watch?v=7ErgkuUwUUc&feature=youtu.be 

Identifying and Managing Arthropod Pests in Hemp with Heather Darby and Scott Lewins of the UVM Extension Northwest Crops and Soils Program (9 Jul 2020) 74 views https://www.youtube.com/watch?v=KbKbDkEwk2I&feature=youtu.be 

Identification and Management of Disease in Hemp with Ann Hazelrigg, UVM, and Chris Motyka (30 Jul 2020) 77 views https://www.youtube.com/watch?v=wouZy-3Ioxk&feature=youtu.be 

CBD Post-Harvest Handling (Drying Focus) with Chris Callahan, UVM (6 Aug 2020) 829 views https://www.youtube.com/watch?v=dIPozbV-MuY&feature=youtu.be 

Hemp Sampling Pre-Harvest with Robert Shipman and Michael DiTomasso of the Vermont Agency of Agriculture Food & Markets (13 Aug 2020) 96 views https://www.youtube.com/watch?v=9NFlbdJyS-w&feature=youtu.be 

Hemp Testing at Certified Labs with Robert Shipman and Michael DiTomasso of the Vermont Agency of Agriculture Food & Markets (10 Sep 2020) 39 views https://www.youtube.com/watch?v=LNw_4wQojB0&feature=youtu.be 

Due to the pandemic, we were unable to host in-person events during the growing season. Instead our team pulled together a series of Virtual Friday Field Days. Hemp was highlighted at the 14-Sep. Field Day Friday. The event was attended by 31 stakeholders and the archived video on YouTube has been viewed 71 times since it was posted. Virtual Field Day Fridays 2020

In the spring of 2021, a series of webinars focused on hemp production was delivered to stakeholders during the summer. There were 3 webinars held from June through September. The goal was to provide timely information to growers related to production and regulation. 

Growing High Quality Hemp Starts with Gretchen Schimelpfenig, Lauren Tonti, and Chris Callahan. (12-April, 21). 57 attendees & 225 views. https://www.youtube.com/watch?v=aih9_Dytzdg

Hemp Irrigation Systems with Gretchen Schimelpfenig. (11-May, 21) 36 attendees & 125 views. https://www.youtube.com/watch?v=-vNQDsHfCW4

Development of Triploid Seedless Hemp Varieties. (20-May, 21) 43 attendees & 215 views. https://www.youtube.com/watch?v=Ny1_ZUyEQOU

On August 10, 2021 a hemp field day was hosted at Borderview Farm. There were 65 attendees from 3 states. Farmers were able to tour hemp research trials including fertility, variety, and pest management trials. In addition, a scouting intensive was held to help farmers and PDP participants learn more about pest identification and pest management. Harvesting and processing equipment were also demonstrated. Hemp Field Day - 2021.

Several blog posts were developed and posted to the UVM OutCroppings Blog. There are 195 subscribers.

Crop Insurance for Hemp Growers (Jan 2020) https://blog.uvm.edu/outcropn/2020/01/09/crop-insurance-for-hemp-growers/ 

Growing Hemp Update and COVID-19 (Apr 2020) Update https://blog.uvm.edu/outcropn/2020/04/30/growing-hemp-update-and-covid-19-update/ 

Potato Leaf Hoppers Have Arrived! (Jun 2020) https://blog.uvm.edu/outcropn/2020/06/24/potato-leafhoppers-have-arrived/ 

The European Corn Borer in Hops and Hemp (Jul 2020) https://blog.uvm.edu/outcropn/2020/07/02/the-european-corn-borer-in-hops-and-hemp/ 

Determining the Sex of Hemp Plants (Jul 2020) https://blog.uvm.edu/outcropn/2020/07/22/determining-the-sex-of-hemp-plants/ 

Industrial Hemp Regional Scouting Pest Survey update  (Aug 2021) https://blog.uvm.edu/outcropn/2021/08/30/industrial-hemp-regional-pest-survey-update/  

The Important of Yeast and Mold Testing in the Hemp Industry(Nov 2021) https://blog.uvm.edu/outcropn/2021/11/02/the-importance-of-yeast-and-mold-testing-in-the-hemp-industry/ 

 

Several research reports and factsheets were developed and posted to www.uvm.edu/extension/nwcrops.

Darby, H. 2020. Industrial Hemp for Flower Production: A guide to basic production techniques. University of Vermont Extension Northwest Crops and Soils Program. St. Albans , VT. https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/Articles_and_Factsheets/2020_Hemp_101.pdf (July 2020)

Darby, H. 2020. Industrial Hemp Record Keeping Booklet. University of Vermont Extension Northwest Crops and Soils Program. St. Albans, VT. https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/Industrial%20Hemp/Hemp_Record_Keeping_Booklet_FINAL_050620.pdf (accessed 15 Dec 2020) 

Darby, H., Bruce, J., Lewins, S. and S. Ziegler. 2020. Hemp Flower Nitrogen Fertility Trial. University of Vermont Extension Northwest Crops and Soils Program. St. Albans, VT. https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/2020%20Research%20Reports/2020_Hemp_Nitrogen_Fertility_Final.pdf (accessed 7 Dec 2021).  

Darby, H., Bruce, J., Hazelrigg, A., Krezinski, I., Lewins, S., Malone, R. 2020. On-Farm New England Hemp Pest & Disease Scouting Report. University of Vermont Extension Northwest Crops and Soils Program. St. Albans, VT. https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/2020%20Research%20Reports/2020_Hemp_On-Farm_Scouting_Report_Final.pdf

 Darby, H. 2020. The European Corn Borer in Hops and Hemp. University of Vermont Extension Northwest Crops and Soils Program. St. Albans, VT. https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/Articles_and_Factsheets/European_Corn_Borer_Hemp_Hops_factsheet_FINAL.pdf (accessed 15 Dec 2020) 

Darby, H. 2020. Common Pests in Industrial Hemp. University of Vermont Extension Northwest Crops and Soils Program. St. Albans, VT. https://www.uvm.edu/sites/default/files/Northwest-Crops-and-Soils-Program/Industrial%20Hemp/Hemp_Bulletin_-_Managing_pestsfinal.pdf (accessed 15 Dec. 2020) 

Learning Outcomes

75 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key areas in which farmers reported changes in knowledge, attitude, skills and/or awareness:

Pest identification, fertility amendments, reading a soil test, how to take a soil test, pest management options.

The pandemic shifted much of our outreach remotely but we still were able to provide farmers with high quality education. We focused on various topics such as fertility management, taking soil samples, and reading a soil test over several educational events. Attendees were surveyed post event and the number of farmers indicating changes in knowledge were recorded. 

Project Outcomes

28 Farmers changed or adopted a practice
2 Grants applied for that built upon this project
2 Grants received that built upon this project
$400,000.00 Dollar amount of grants received that built upon this project
3 New working collaborations
Project outcomes:

Through the project we worked closely with several producers that were experiencing significant disease challenges in 2020. Over the winter months our project team working one-on-one with the farms to develop IPM strategies for management of the diseases. This included modifying planting spacing, shifting varieties, and also moving locations. We scouted the fields closely in 2021 and farmers were very pleased with the results. Prior to this they had no experience with proper scouting techniques and other practices to minimize disease. One farmer stated that we saved their business. The disease Septoria had nearly eliminated their 2020 crop. They had no idea what the disease was but working with our team allowed them to properly identify the disease and develop a management plan. 

In addition, we assisted farmers with learning how to soil sample, followed by them taking samples, and working with our team to develop fertility recommendations that were subsequently implemented by the farm. 

 

 

 

Assessment of Project Approach and Areas of Further Study:

Fertility recommendations and requirements of hemp is still largely void of research information. The two year's of data did not provide consistent enough results to make conclusions as to minimum application rates to produce a high yield and quality crop of hemp for flower. Although the results suggest that in some year's CBD and THC could be suppressed by rates of nitrogen over 100 lbs per acre in a second year this same result was not obtained. This may possibly be due to differences in weather between years or background fertility.  Future work needs to be focused on adaptive management tools or in-season tools that can help farmers make decisions on further nitrogen fertilization. Developing tools similar to a Pre Sidedress Nitrate Test used in corn would be a excellent approach for hemp.

Further investigation of suitable IPM practices for hemp are critical to success of farms. Our project helped to identify major disease and pest issues on farm and started to help farmers gain confidence in how to scout, what are pests and what are beneficial insects, lifecycle of pests, and potential management. However, more outreach needs to be done to educate farmers. More research is needed to help farmers manage the extensive list of pests that can harm hemp. Research on cultural practices, resistant varieties, and also potential chemical controls.

Lastly research to investigate cultural practices, such as cover crops, should be further explored to understand the impact that these conservation practices could have on reducing fertilizer applications, suppressing weeds, and managing disease.

 

 

Information Products

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.