Evaluating Organic Pest Control Products for Strawberries in Combination with High and Low Tunnels for Limited Resource Farmers in the Mid-South

Final report for LS16-275

Project Type: Research and Education
Funds awarded in 2016: $246,413.00
Projected End Date: 08/30/2019
Grant Recipient: Texas A&M University
Region: Southern
State: Texas
Principal Investigator:
Dr. Russell Wallace
Texas A&M University AgriLife Extension
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Project Information

Abstract:

     The project was a collaborative effort led by Texas A&M AgriLife Extension (TAMU) with collaborators including the University of Arkansas (UA), Prairie View A&M University (PVAMU), the Strawberry Poteet Festival Association and the Texas Organic Farmers and Gardeners Association (TOFGA). This report covers the third and final year of the 3-year project and summarizes our overall efforts. The objective of our project was to evaluate commercially available biocontrol products for efficacy, yield and cost in strawberries, as well as provide outreach training for growers in Texas and Arkansas. Our target audience was limited-resource, small-acreage farmers in the mid-south who struggle with organic strawberry production. Over the past three years we have conducted and attended many conferences, workshops and field days, and presented information derived from this SARE project to over 200,000 mid-south growers, gardeners and other stakeholders through our outreach and media efforts.

     The project received a no-cost 6-month extension due to Season 3 trials not being completed until June or July 2019. Up to nine growers (2 in Arkansas and 7 in Texas) as well as two Texas county extension agents (Tarrant and Atascosa counties) and other TAMU faculty participated in the project by assisting with on-farm trials, at research centers, and by participating in field days and workshops. Across Texas, farmer trials included locations in South Texas (Hempstead), North Texas (Arlington), South Central Texas (Poteet) and the Texas High Plains (Lubbock). Grower participation changed over the course of the project due to several dropping strawberries from their farm production in the second/third years; however, new growers were recruited and participated.

     Approximately twenty-three on-farm and research center strawberry trials evaluating biopesticides were planned and conducted over the three-year project. Several trials were canceled due to untimely flooding, weather-related conditions (heavy rains and/or drought), animal damage or a lack of pests which prevented collaborators from obtaining effective data. Even so, it is anticipated that at least two peer-review publications will result from data collected during this project and submitted to scientific journals within the next six to 12 months.

     Outreach for the project was extensive and very successful. It included conferences, workshops, field days, local radio/TV, scientific presentations and site visits by growers and supporting industry (biopesticide manufacturers/distributors). The project guide entitled ‘Applying Biocontrol Products in Mid-South Strawberries’, however, is still in preparation and was delayed due to late 2019 harvest and data analysis, as well as the undergraduate student assigned to prepare the first draft left the program recently. However, it should be completed within 3 - 4 months of this report.

     Finally, further funding was acquired as a result of this project from a Texas Dept. of Agriculture SCRI Block Grant, and Wallace was invited twice with US-AID Farmer-to-Farmer projects to visit Timor-Leste, provide leadership in developing their country’s strawberry production guide and collaborate to improve organic grower’s production through farm visits and training.

Project Objectives:

     The overall objective of the project was to enhance the economic and environmental sustainability of limited-resource farmers growing organic strawberries through sustainable practices in high/low tunnels or in open field production. There are five sub-objectives which include working collaboratively with three or more limited-resource organic strawberry growers in Texas and Arkansas, and conduct research trials at Texas A&M AgriLife Extension, Prairie View A&M University and the University of Arkansas.

Our objectives are to:

     (1) Select biocontrol products and evaluate their efficacy on strawberries grown in high tunnels or under low tunnel protective covers for disease and insect control in the mid-South;

     (2) Evaluate the costs of application using the selected biocontrol products and determine their cost-effectiveness in organic strawberries. Products must be economical to be sustainable;

     (3) Provide training opportunities for our growers, Extension agents, and crop consultants with on-farm demonstration trials, field days and the opportunity to share results and thoughts on the products through annual workshops and conferences;

     (4) When trials are completed annually, we will analyze and summarize all the collected data to report at our planned events, or at regional and national scientific horticulture meetings through submitted abstracts or peer-review publications; and

     (5) Upon completion of the 3-year project we will provide our limited resource farmers and other region-wide stakeholders with up-to-date scientifically-researched recommendations on current biocontrol products and finalize the project by preparing and publishing a Biocontrol Guide for Strawberries which will be made available online through our university bookstores (still underway).

Cooperators

Click linked name(s) to expand
  • Dr. Peter Ampim
  • Luke Freeman
  • Heather Friedrcih
  • Dr. Elena Garcia
  • Susie Marshall

Research

Materials and methods:

The project was a collaborative effort involving three land grant universities in Texas and Arkansas and included field research, on-farm demonstration trials and outreach activities including conferences, workshops and field days, and farm visits. The project also included county agents and farmers in both states. Research trials were conducted at the University of Arkansas, Texas A&M AgriLife Research & Extension Center and Prairie View A&M University farms. Approximately 23 research trials were conducted using randomized complete block designs or split-plot designs, though not all were successful. On farm demonstration trials were conducted in both Texas and Arkansas on limited resource farmer's fields. Strawberry plants were obtained through commercial nurseries, and in most cases the same varieties were used in all trials. Trial planting generally occurred from early October through mid-November depending on local rain conditions. All plots were maintained as close to commercial production (fertilizer, row spacing, cultural practices) as possible. Trials were evaluated in both high tunnel and low tunnel.open field production systems. Commercially available biocontrol products that listed control of insects and diseases were evaluated and applied according to their labels for strawberry production. Over the three years of the project, these products included organically labeled active ingredients such as Trichoderma species, Bacillus species, Streptomyces species, Ulocladium species, tea tree oil, potassium bicarbonate, mineral oils, peroxide and acetic acid, extracts of Reynoutria, Calcium, Boron, copper hydroxide, garlic and other oils. etc. Often we collaborated with biocontrol industry and manufacturers to obtain products and ensure treatments were applied correctly. Treatments were applied for foliar diseases to randomized plots using hand-held backpack single-nozzle sprayers to the leaves of strawberry plants according to label or manufacturer instructions. When applying products for root disease control, products were applied using a CO2-charged backpack system that was adapted to fit into the drip system for each plot. Products were applied using a water carrier either 3 or 6 times during the season. Disease and insect control were evaluated throughout the cropping season and into harvest. In some cases, plant weights, crown numbers were recorded. In all trials, yield data included number of marketable and unmarketable fruit, number of diseased fruit (Botrytis), total weights, diseased/dead plants, plant vigor and insect populations. 

For the most part, research trials concentrated on disease control largely due to the fact that insect populations were inconsistent. Spider mites were an issue only once at Texas A&M in Lubbock, and populations were not distributed well.

For field days, workshops and conferences, project collaborators conducted these at their unique locations and including planning and organization, advertisement, set up, and organization of presenters and tours. Other outreach components included accepting and volunteering to give presentations at conferences and scientific meetings throughout the course of the project.

Research results and discussion:

Analysis and an overview of the results of the project indicated several trends. First, insect populations were generally low, but in some cases overall populations of spider mites and Lepidopterous worms were observed to be higher in high tunnels compared to open field plots. This was likely a result of an improved growing environment for the developing insects. In fact, spider mites were observed generally 2 - 3 months earlier inside high tunnels compared to open fields. Spider mite control was generally poor, but products with a plant or mineral oil base were generally more effective. These products controlled mites through smothering or direct contact. Poor control may have been a result of spider mites presence under the leaves, which can often be difficult for sprays to reach. In one trial in Texas, worm control was best in plots sprayed with Grandevo bioinsecticide, though this control was still not commercially acceptable.

Product evaluation results from disease control trials were variable, and depended on university location as well as location of either inside a high tunnel or in the open field. Similar to insect populations diseases including root rot (Rhizoctonia) in Lubbock and Botrytis gray mold were influenced by the micro climates of the tunnel production system. Inside tunnels, where humidity around the strawberry crown and roots was higher (less air movement, etc.), Rhizoctonia root rot was significantly higher compared to open field plots. However, the opposite occurred with Botrytis gray mold. In the open field plots, where rainfall was allowed to contact leaves and fruit, Botrytis gray mold fruit damage was significantly higher compared to high tunnel strawberries. In Arkansas, during two years of research, the biocontrol products failed to provide any significant control or improve disease control over the chemical treatments. Marketable and cull yields did not differ between treatments. At Prairie View, in 2017, all biocontrol products increased yields significantly compared to the chemical control, and this was a trend for all variables evaluated including fruit number, marketable weights, and percent marketable yield. However, this trend did not continue during the following seasons of the project.

At both the Lubbock and Prairie View locations, RootShield Plus and Double Nickel gave the closest or similar responses to chemical treatments (Abound + Ridomil Gold). While the chemical treatment had the highest total yields, in both locations RootShield Plus and Double Nickel were close in marketable number and yield.This indicates that these two products in particular, are good choices in strawberries for controlling potential diseases, or at least, improving strawberry plant growth so that production is equal or similar. For organic growers, these are good options.

Thus, the biocontrol products Double Nickel (Bacillus amyloliquifaciens) and RootShield Plus (Trichoderma spp) performed best compared to all other products evaluated. RootShield Plus in all 3 years of the project performed better than most other products when evaluating plant growth and strawberry yield. Double Nickel performed well in both years it was in the trials as well. In most cases, control of Rhizoctonia root root (Lubbock only) was not adequate compared to the chemical control, however, because plant health was often increased using RootShield Plus, yields were similar or higher in some trials. This is a significant and important result for organic growers who do not have chemical control options for root diseases. Increased crown number and health can often be associated with higher yields. However, in our trials we did not see any such observations.

For Botrytis fruit rot control, high tunnels provided better control than the applications of either chemicals or biofungicides. This is a result of no rainfall hitting the developing flowers and fruits which stimulate Botrytis infections. In fact, in Lubbock, Botrytis infections only occurred following rainfall events. Therefore, for small acreage organic growers, it suggests that to reduce Botrytis fruit rot (and likely other fruit diseases) that plasticulture using high and/or low tunnels during rain events will have just as a significant effect at reducing diseases as chemicals or biofungicides. Overall, no biofungicides applied for Botrytis control decreased fruit infections compared to the chemical control.

In the final year of the project, we searched the internet for the potential to purchase these products and found average prices. As a result, we were able to determine average costs of these biofungicide products on an application per acre. The minimum average price per application was determined to be about $29/A, which is somewhat cheaper than the minimum average for the root disease chemical treatments ($37/A). Most conventional growers will use foliar products that range between $7 - $25/A. However, with the chemical treatment, at most three applications can be made ($111/A), while for each of the biocontrol products, depending on the disease, weekly applications over the course of the cropping season (20 weeks) is suggested. Thus, the number of applications depends on the targeted disease and with the biocontrol products, costs will likely increase. Also, we determined that for Rhizoctonia root rot control, three applications of the most biofungicides had equivalent control as 6 applications, so cost savings could be realized with fewer applications. Thus, for limited resource farmers, the costs of these biocontrol products, if used according to label instructions, can be potentially prohibitive.

Overall, the results of this 3-year project are encouraging, especially for controlling root diseases and improving plant health. Two products for root disease control stood out against the others, and this included Double Nickel and RootShield Plus. For Botrytis fruit rot control, the products evaluated did not improve control over the chemical treatments nor compared to non-sprayed plots. Finally, for limited resource growers, purchasing tunnels, either high tunnels or low tunnels while somewhat expensive, may benefit in reducing fruit diseases during rainfall events, but care should taken, and biocontrol products used to prevent root disease infections where possible.

Participation Summary
7 Farmers participating in research

Education

Educational approach:

Overall, education was a significant effort in this project and was accomplished by all three university collaborators. At all our education events, we invited industry professionals, growers, home gardeners, potential growers and consumers to observe the projects coordinated by all three collaborating universities. In both Texas and Arkansas, during conferences and field days, participants were trained and given information regarding the project, the they observed first-hand demonstrations of the biopesticide trials. We prepared PowerPoint presentations for training as well as developed handouts specifically targeted to the audiences and topics that were to be discussed. In some cases, although biopesticides were the targeted topics, participants were also able to be trained on general strawberry production techniques to augment

Project collaborators from all three institutions held educational programs including approximately three conferences, six workshops, sixteen presentations and five field days. Invited presentations were given at nine conferences including at national, regional and local meetings, and at seven grower meetings. A SARE Strawberry Workshop was held at Hope, Arkansas in March 2017 and in April 2018 at Lubbock. Annual workshops were held in Texas at Lubbock, Poteet and Prairie View. Field days included hands-on approaches with classroom teaching followed by visits to field trials as well as cooperating grower’s fields. Our efforts also included several biocontrol companies who provided product samples and materials for workshops and conferences at times during the project.

In Arkansas, the project was also highlighted in the 2019 Horticulture Industry Show (HIS). Graduate student Karlee Pruitt had the opportunity to attend and present at the North American Strawberry Growers Association consortium in Orlando, Florida. A poster of her research results was presented in Las Vegas, NV at the National Amer. Soc. for Hort. Sciences titled “The Efficacy of Different Combinations of Biological Pesticides for High Tunnel Production of Strawberries in the Mid-South”. Tours of the project also included students from a two-year college, a high school, the University of Arkansas Horticulture Department and multiple students have had the opportunity to work within the project by helping harvest, taking data, and learning about the project.

At Prairie View A&M there were 3 – 4 tours annually involving growers and school groups, taste testing, and cooking demonstrations. Undergraduate students at PVAMU presented posters on various aspects of the project at the 2017 TAMU Annual Pathways Student Research Symposium and at the 2019 ARD Research Symposium in Jacksonville, Florida and received third place in the Plant Health and Production and Plant Products undergraduate poster session. It is estimated that over 200,000 public stakeholders were exposed to the three-year project.

At Lubbock, annual field days were held that demonstrated current research and included approximately 6 events. For educational purposes, we are still working on the Biocontrol in Strawberries Guide, which we anticipate will be ready for online publication in 4 - 4 months.

Educational & Outreach Activities

150 Consultations
5 Curricula, factsheets or educational tools
9 On-farm demonstrations
3 Published press articles, newsletters
10 Tours
19 Webinars / talks / presentations
8 Workshop field days
10 Other educational activities: Unplanned grower visits to research farm to evaluate strawberry production and discuss pest control using chemicals and/or biopesticides.

Participation Summary:

350 Farmers
15 Ag professionals participated
Education/outreach description:

Based on our outreach programs, we had multiple calls from growers, consumers, gardeners, and industry professionals related to our project. As a result of this project, we estimated that an additional 20 small acreage growers are producing strawberries in Texas, primarily around the Poteet region. Our on-farm demonstrations were successful in showing local growers strawberry production using biopesticides, and the benefits and disadvantages of their use.

Outreach was conducted via email blasts to growers and grower organizations by agents and Texas Organic Farmers and Gardeners Association. Overall media outreach was primarily conducted through PI Wallace at Texas A&M AgriLife. The project was discussed in the media and presented multiple times during the 3 years on West Texas Ag radio (AM950- Lubbock), on TV Fox34 News (Lubbock), and the Texas Farm Bureau radio program (multiple segments). It was also presented through multiple press releases by articles written by Texas A&M AgriLife Ag Communications.  An overview of the SARE strawberry project was presented at the Texas Organic Farmers and Gardeners Association Conference in 2018, and also annually at the ASHS scientific meetings held in Hawaii, Washington DC and Las Vegas. We plan to continue to use the data and observatoins from this project in our presentations at upcoming field days including two in November 2019, and others planned for spring 2020 in collaboration with our Texas Dept. of Agriculture SCRI Block Grant Program project. Currently, we have plans for two upcoming scientific journal articles on the root disease and foliar disease trials. University of Arkansas graduate student Karlee Pruitt has a planned thesis defense as well as publication of her Masters Thesis shortly.

Learning Outcomes

15 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key changes:
  • Knowledge: Prior to this project, many mid-southern growers were either unaware or had little knowledge of the potential benefits that biocontrol products offered in organic strawberry production. Many did not realize that they had these options and whether they were efficacious and cost effective. Most farmers in the region are small-acreage (10 acres or less) growers with limited resources, including land, equipment and labor. After viewing research trials and listening to project results at workshops and conferences, and discussing the evaluated products, most growers understand biopesticide’s potential for use and their modes of actions. They also determined whether these products were good fits for their individual farms. Several have purchased a few of the highlighted and successful products for trials on their own farm.

    Skills: While some growers had used biopesticides previously, most had not. Those that did had limited success, though a few mentioned good successes. Through our training, we demonstrated appropriate techniques to apply these products as well as which ones were more efficacious from our trial results. We also trained them to select products that will best fit their needs and farm, while staying within their projected budgets. Through our trainings, most growers realized there is no silver bullet for controlling diseases and insects, and that with biocontrol products, timing, appropriate application, environment and proper storage of products was essential to successful control. Growers were taught the differences between preventative and curative controls with biopesticides, and most understood the skills needed for that approach.

    Attitude: Most growers who attended our programs were at least aware of biopesticides and most had specific opinions on their use, generally an unfavorable opinion. These included (1) biopesticides don't work; (2) I've been told they work by salesmen, but never not on my farm, (3) these products may work but are too expensive to use and too risky, (4) some of these products work pretty well. Our results were similar to these opinions, though we did find that several products (Double Nickel and RootShield Plus) worked fairly well. In many cases, the products failed to perform to adequate standards, while with others, they worked under specific environments and applications. In a survey conducted by Ampim at PVAMU, following his presentation and field visits, 50% of the workshop participants considered or were willing to try the organic products discussed, and 63% of the participants thought using organic products was beneficial. This was a similar response to attendees at Lubbock field days and workshops. Thus, this project helped to dispel several myths about biopesticides not working and was important in changing some of the attitudes of small acreage strawberry growers.

Project Outcomes

35 Farmers changed or adopted a practice
1 Grant received that built upon this project
15 New working collaborations
Project outcomes:

Throughout the course of the project, most trial results showed only a few significant differences between disease control treatments, and there was no consistency between locations in Texas and Arkansas. However, significant outcomes included:

  1. Environment (both micro and macro) play an important role in the efficacy of the products. Using high/low tunnels to reduce fruit diseases especially during rain events or in areas where rainfall is high; or using RootShield Plus or Double Nickel biofungicides can increase marketable yields through improved growth and in some cases, improved disease control. However, high tunnels may increase potential root diseases, so care and aggressive scouting and crop rotation are needed. Plasticulture may have more impact than biofungicide use.
  2. Bioinsecticide trials were not as successful as the disease control trials, therefore, no real observations were made. However, it was noted that plant extracts or mineral oils would likely perform better if applications were made to the lower sides of strawberry leaves.
  3. Costs of biofungicide products for foliar disease control per application are not necessarily higher than conventional applications; however, costs for biofungicide programs can be prohibitive for limited resource farmers as there is generally a need for a higher number of sprays for improved control which drives up the overall costs.
  4. Growers were trained on modes of actions of biocontrol products, their benefits and limitations and their appropriate use.
  5. When using biofungicides for root disease control, growers can save costs by applying products approximately 3 - 4 times per season rather that 6 or 7 times. Results indicated similar control and yield responses.
  6. Growers continue to be interested in biocontrol products, especially if they are producing strawberries organically. However, most limited resource farmers are still hesitant to pay the initial prices for these products.
  7. The general public was made aware of grower's willingness to provide organically grown strawberries to local markets. This increased awareness also increased the number of growers wanting to produce strawberries, as well as an increased demand for locally grown berries at the farmer's markets.
  8. This project resulted in the successful funding of a Texas Department of Agriculture SCRI Block Grant Program funding from 2018 - 2020.

 

Recommendations:

Strawberries continue to be an important source of income for limited resource farmers. Future studies could evaluate additional commercial products, as more and more continue to be produced. These products should be evaluated under additional types of environments including the northeast, northwest, mid-central US, etc. While this project suggests good benefits from several of these products, their success is limited at this point to this region. More evaluation on the interactions of diseases, biofungicides and high tunnels would be beneficial. Finally, high costs of weed control are limiting profits for small acreage strawberry growers and projects evaluating bioherbicides would be useful.

 

 

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.