- Vegetables: spinach
- Pest Management: biological control, biorational pesticides
Across the Northeast, growers are struggling to meet the ever-increasing demand for fresh produce year-round. High-tunnels are being used more-and-more to increase production of spinach and other greens for harvest all winter long. This environment presents many challenges, with disease management being often identified by growers as a critical research need. We have observed that damping-off is a particularly important disease, causing reduced germination that often requires growers to re-seed, potentially missing the narrow window for successful establishment of a winter spinach crop and thus drastically reducing yields. Seedling blight caused by Rhizoctonia solani and leaf spots such as Cercospora and Cladosporium build up in tunnels where spinach is grown year after year, reducing marketable yield and quality. In the proposed studies, UMass Extension will partner with an experienced winter greens producer to evaluate efficacy of biopesticides to improve germination, reduce disease severity, and improve yields in winter-grown spinach. Three to five biopesticides will be used preventatively as pre-plant soil drenches and will be evaluated alone and in rotation with a contact, foliar-applied biopesticide. A lab assay will be conducted to determine the effects of low temperature on growth of biocontrol organisms that comprise the biopesticide products. Results will be shared with growers via newsletters, factsheets, and through grower presentations. The objective of this study is to generate information that will help growers across the Northeast meet market demands for quality greens throughout the winter by using reduced-risk pesticides to control common diseases in winter spinach systems.
Project objectives from proposal:
The goal of this study is to determine the efficacy of biological pesticides to control important soil-borne diseases and increase yield in overwintered, high-tunnel greens production systems. We will evaluate three to five OMRI-approved, soil-applied biopesticides compared to an untreated control. The study will be conducted in a commercial high tunnel in partnership with a farmer who has grown winter spinach for fresh market sales for over five years. Additionally, a supplementary assay will be performed in the laboratory growth chamber in order to determine the effect of low temperature on growth rate of various commercial biocontrol organisms. The objective of this study is to generate information that will help growers across the Northeast produce higher yields and higher quality greens throughout the winter by using reduced-risk pesticides to control common seedling diseases.
Specific objectives are to:
- Determine if there is a lower temperature limit past which the biocontrol organisms become inactivated and other control strategies should be used, or if certain biocontrol organisms are more cold tolerant and would thus be better suited for use in winter production systems.
- Find out if any of the products evaluated can significantly increase crop yield and quality.
The field experiment will be carried out in one 36’ by 200’ high-tunnel at Queen’s Greens Farm in Amherst, MA from September 2015 through April 2016. Soil will be tested in early-September 2015 and compost, fertilizer, and lime will be added according to soil test results to provide adequate fertility and pH for spinach production based on the New England Vegetable Management Guide recommendations for the crop. ‘Raccoon’ spinach seed will be directly seeded in mid- to late-September by the farmer. Spinach will be seeded into seven 5 foot wide beds with eight rows of spinach per bed and plants at a density of about one plant per inch of row.
A randomized complete block design with four replicates of each treatment will be used. The high tunnel will be broken up into four, fifty foot long blocks, with each replicate plot consisting of 50 feet of one bed. Soil-applied treatments (see Table 1) will be applied to the soil, lightly incorporated, and watered in as part of the bed-forming procedure just prior to seeding using the highest labeled rates. Subsequent treatment applications will be made biweekly or monthly according to product labels, growing conditions, and disease pressure. Post-plant applications will be made by mixing products with water and spraying over the plants, covering the foliage and targeting the base of plants and soil according to the product labels. A contact, foliar-applied biopesticide such as Oxidate will be included and tested alone and in rotation with soil-applied products, in order to determine effect of combining preventive soil applications with contact foliar applications of biopesticides. We anticipate being able to evaluate all seven of the treatments listed in Table 1, but realize it is an ambitious goal for an on-farm trial where plans can change and things come up. We are confident that we can evaluate at least three products compared to an untreated control given the minimum high tunnel space and other resources that will be available.
Plants will be observed daily by the farmer and disease ratings will be made at least monthly, or more frequently if deemed necessary to capture disease progress. Incidence of pre-emergence damping off will be measured by assessing the percentage of seedlings emerged per plot at seven and fourteen days after seeding. Severity of post-emergence damping-off will be measured by assessing the percentage of emerged foliage affected by disease (e.g. stem and leaf lesions, wilt, discoloration, fungal growth) on subplots consisting of 5 feet of bed of the interior 4 rows of spinach. Yield data will be taken at two to five time-points throughout the growing season, depending on growing conditions and the number of cuttings achieved. Subplots measuring 2.5 feet in length and 4 rows wide will be established in the center of each main plot in order to assess yield at each harvest period. Yield will be measured by recording the total weight of the harvested material. Since the experiment will be carried out on a commercial farm and the produce is to be sold, it will not be possible to take dry weights to assess yield.
Relative humidity and temperature will be measured throughout the duration of the study using programmable data loggers placed in each control plot to record relevant conditions and will be used to correlate disease incidence and severity to environmental conditions.
The farmer will be responsible for maintaining crop health throughout the season as far as fertilization, irrigation, and will assist in collecting yield data at each of three harvests. UMass Extension staff will be responsible for making all biopesticide applications, collecting weekly disease incidence and severity data, and assisting with the collection of yield data during harvests. UMass Extension staff will be responsible for analyzing data, performing the appropriate statistical tests, and interpreting results. Both the farmer and UMass Extension staff will be responsible for generating outreach materials including an article for Vegetable Notes, a factsheet for the UMass Extension Vegetable Program website, a Plant Disease Management Report and at least two presentations at well-attended, grower-to-grower meetings. UMass Extension staff will be responsible for presenting to extension and academic plant pathologists at the annual meeting of the Northeastern Region Division of the American Phytopathological Society.
Each of the biocontrol organisms in the products being evaluated in the field experiment will be subjected to a growth assay performed at the University of Massachusetts by UMass Extension staff. UMass Extension staff will attempt to grow out each of the organisms on solid or liquid growth media in temperature and humidity controlled growth chambers. Once these isolations have been successfully carried out under optimal growth conditions, these cultures will be grown at a range of temperatures from 21° C to 0° C, in order to determine the lower range for growth of these organisms. Plates will be assessed every 4-7 days and the diameter of growth of the colony will be recorded for fungal cultures and number of colonies on serial dilution plates for bacterial cultures. UMass Extension staff will be responsible for performing all lab work including culturing organisms, collecting weekly growth data, analyzing data, performing the appropriate statistical tests, and interpreting results.
Both the farmer and UMass Extension staff will be responsible for generating outreach materials including an article for Vegetable Notes, a factsheet for the UMass Extension Vegetable Program website, a Plant Disease Management Report and at least two presentations at well-attended, grower-to-grower meetings. UMass Extension staff will be responsible for presenting to extension and academic plant pathologists at the annual meeting of the Northeastern Region Division of the American Phytopathological Society.
The project period will start April 1, 2015 and will go through February 28, 2017.
The lab experiment will be conducted from April through June of 2015. In the event that the biological control organisms are very difficult to grow on solid media in the lab, this piece of the project can be continued over the winter of 2016-2017. The lab experiment is solely the responsibility of UMass Extension staff.
Planning of the field experiment will commence in April 2015. Planning will be done collaboratively by the farmer and UMass Extension staff and will include ordering seed, determining planting strategy and crop production practices, and procuring biopesticides from chemical companies and specifying methods of application, and solidifying methods for data collection. Soil testing and amendment with compost, fertilizers, and lime will occur in August and September of 2015. UMass Extension staff will assist with soil sampling and interpretation of results, while the farmer will be responsible for applying and incorporating any soil amendments deemed necessary. The first biopesticide applications will be made by UMass Extension staff, with the assistance of the farmer by incorporating and watering-in materials just prior to direct-seeding of crop in mid to late-September 2015. The farmer will be responsible for seeding the crop at the appropriate rate and spacing during mid to late-September. The farmer will be responsible for maintaining the crop in terms of insect pest management, weed management, irrigation, and fertility for the duration of the experiment, from September 2015 through April 2016. The spinach crop will be monitored by UMass Extension staff for pre- and post-emergence damping-off throughout the period of growth, September 2015 through April 2016. Collection of yield data will occur at two to five time-points throughout the growing period, depending on crop growth and the number of cuttings achieved from December 2015 through April 2016. Data will be analyzed for statistically significant treatment differences during April and May of 2016 by UMass Extension staff.
Written outreach materials including an article for Vegetable Notes and a factsheet for the UMass Extension Vegetable Program website will be drafted over the summer of 2016 for publication in August or September of 2016, to coincide with planting of the next years’ winter spinach crop. Results will be presented by UMass Extension staff and the farmer at the Frozen Ground Winter Grower’s Conference in August 2016 if possible, by UMass Extension staff at the regional meeting of the American Phytopathological Society in October 2016, and at the NOFA-MA Winter Conference in January 2017. A final report will be written collaboratively by the farmer and UMass Extension staff during February of 2017.
Results of these studies will be shared with growers and extension personnel across the region through both written and oral reports. A summary of project outcomes will be submitted to Plant Disease Management Reports, a peer-reviewed journal containing results of fungicide efficacy trials that is widely read by extension staff nationally. An article detailing the project goals, methods and results will be written for the UMass Extension Vegetable Program’s newsletter, Vegetable Notes, which has a readership of over 2,000 growers, home gardeners, extension personnel and other ag service providers from across the Northeast. Additionally, a factsheet will be created and housed on our UMass Extension Vegetable Program website. UMass Extension staff will present the project outcomes to extension personnel and plant pathologists across the Northeast at the annual meeting of the Northeast Division of the American Phytopathological Society. Additionally, UMass Extension staff and the farmer will collaborate to present the outcomes of the project at a minimum of two annual growers meetings: the Frozen Ground Winter Growers meeting which brings together extension personal and leading farmers working in winter production; as well as at the annual winter meeting of the MA chapter of the Northeast Organic Farming Association which is a major conference for organic growers across the state and across the region. Additional presentations may be given at annual winter meetings of the New England Vegetable and Berry Growers’ Association, which occur across MA and NH throughout the winter each year and bring in a large audience of organic as well as conventional growers, but funding is not being requested from SARE to cover these costs.