Sustainable pest management in high tunnel winter greens production

Final Report for LNE10-302

Project Type: Research and Education
Funds awarded in 2010: $79,668.00
Projected End Date: 12/31/2013
Region: Northeast
State: New York
Project Leader:
Judson Reid
Cornell Vegetable Program
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Project Information


The increase in production of winter greens, such as spinach, in high tunnels and greenhouses across the Northeast has increased farm revenue and community access to locally grown product year-round. However, unique winter pest infestations are restricting farmers’ economic potential.

This project enhanced farm sustainability by researching and documenting natural pest management with 24 on-farm demonstrations over 4 seasons. Information generated from this work such as relative varietal pest susceptibility; releases of biological controls and biorational pesticides; were promoted through farm visits, on-farm demonstrations, winter meetings and newsletter articles. 21 different educational events taught 516 people project content. Project staff made over 100 farm visits. Additionally 6 newsletter articles, multiple Tweets and 1 online aphid management factsheet were created. As a result of these efforts 24 high tunnel growers were documented to have adopted biological or biorational control methods to manage pests with an average increase in revenue of $2465.13. One survey indicated 61% of increased revenue was attributable to increased awareness and skills in natural pest management.

Challenges experienced include a heightened variability of crop response to weather and management than other types of farming and internal staff turn-over.


Many Northeast vegetable growers are looking for ways to extend their season and provide fresh, locally grown produce to winter CSAs and winter farmers markets. High tunnels are proving to be an excellent way to produce ‘off-season’ greens crops with little-to-no fossil fuel based heat, contributing to environmental sustainability. These production systems also contribute to economic and social sustainability by creating year-round income and maintaining customer relations during the traditional off-season. For example New York State has now over 180 winter farmers market, with greens from hoop houses given credit in a recent USDA report for this success.

Pest infestations, such as aphids and cabbage worms, restrict the economic potential of these systems. As a grower in south west NY put it “Pest management is so much more important in the winter because your losses are so much more”. This project promoted early fall releases of parasitoids, combined with late fall and winter applications of biorational pesticides, specifically Beauvaria bassiana, a commercialized fungal pathogen of aphids. On-farm demonstrations, winter meetings and newsletters promoted these techniques across the state. The project team evaluated adoption and impact on farms contacted through the project.

Performance Target:

Year 1:

    • Educational meetings reach 150 growers; introduce economic benefits of cool season vegetable crops and biological control.
    • 4 on-site grower trials (monitored bi-weekly), technician collects aphid numbers, aphid predation data.
    • 4 Farmers provide percent marketable (clean) crop, and yield in pounds
    • Above data used to narrow effective treatments promoted.
    • On-farm meetings at 2 collaborating farms demonstrate methods to 80 growers.
    • Site visits to 15 entry-level growers.

Year 2:

  • Continue on-site grower trials.
  • On-farm meetings at 2 collaborating farms demonstrate methods to 60 growers.

    • Regional winter meetings present findings to 100 growers.
    • Statewide winter meeting reaches 40 growers.

Year 3:

    • On-farm meeting demonstrates methods to 40 growers.
    • Adoption surveys mailed to 200 growers contacted during the project
    • Adoption verification via minimum of 20 farm visits.

20 high tunnel growers to adopt biological or biorational control methods to manage pests of cool season greens gaining $2000 of marketable product per season.


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  • Elizabeth Buck
  • Kathryn Klotzbach
  • Dr. Brian Nault


Materials and methods:

Case-study farms were recruited in late summer from across New York State. Growers’ experience with winter greens ranged from 0-10 years. 28 farms initiated case-study work with the team project.  However, some farms dropped out due to unexpected changes in production schedule, crop failures, etc.  Over the 4 years, we had 24 different successful case studies (4 farms were participated twice) over 4 winter seasons on 20 farms in 11 counties across New York State.


Pest scouting of warm season crops began at cooperating farms late summer (August-September) in each project year. Target pests included aphids, slugs and lepidopteran pests, which we found to be common in winter greens. Control recommendations were developed with grower input, seeking biological and biorational controls methods.

Crop choice and maintenance were grower decisions. A range of 1 to 3 high tunnels were monitored at each farm. Tunnels were selected based on project fit, cropping history, and grower interest. Plots were established in each crop variety within a given house. Plots consisted of 20-24 plants for spaced plantings (number determined by row configuration) and the equivalent of 3 feet x 1 bed for dense sowings. Crops taking up a majority of the tunnel were allocated 3 plots each, to serve as replicates. Replicate plots were averaged to give more accurate pest pressure assessments. Plots were flagged if the crop was meant to regrow to allow data collection throughout winter. Alternatively, if there would be no regrowth, the plot was reset in an adjacent, unharvested area of the same crop. No plots were moved once the majority of the harvest had occurred.

Plots were scouted biweekly until mid-December, then every three weeks due to slow plant growth and pest activity. Crops that experienced excessive freeze damage were dropped from the scouting schedule. Otherwise scouting terminated when there had been a destructive harvest or when the grower transitioned the tunnel for spring planting.

Scouting was done on a ten-plant and whole plot basis. Ten plants from each plot were randomly selected and examined for pest presence and damage. Aphids were counted across three leaves per plant; one leaf from the oldest, middle, and youngest growth stages. Particular attention was paid to petiole bases for heading crops and spinach, whorls of new growth for pak-choi type crops, and the edges of midribs and small, lower leaf lobes for kale and mustards. This approach was the most effective for detecting aphids. Plot counts of caterpillars and slugs were generated by including those seen on ten plants as well as those readily visible on the crop canopy or ground. Presence of frass was also used to determine pest type, population size, and activity level. Caterpillars were identified when possible. Being mobile pests, the slugs and caterpillars were often not present during scouting. Each plot was assigned a whole-plot feeding damage rating as an indirect measure of pest pressure.   Age of feeding was noted. The overall crop feeding level was noted if it differed substantially from the plot (table 1).

Other pests were monitored as needed by individual farms. Total thrips/plant for 6 plants was counted in alliums. Spinach crown mite (SCM) became a severe pest problem in several locations. (Table 2). A microscopic pest that feeds deep in the crown, the only way to assess SCM population levels was to track feeding damage. Flea beetles were found following eggplants, and decreased without intervention as temperatures dropped. Spider mites were present on some farms the first two winters, and whiteflies were present on one farm. These pests were monitored in the same method as used for aphids. Grasshoppers were present once, and were monitored by counts and frass. Voles were troublesome in the spring in several locations. Traps were recommended for rodent challenges, but damage and control by rodents was not part of this project’s data collection.

Disease became an important factor in the health of the crop and profitability of the production system. Though not an original consideration of this project, disease scouting was added to quantify and help mitigate losses. Disease presence was noted and rated on 0-5 severity scale. Diseases included downy mildew of brassicas; downy mildew of spinach; downy mildew of lettuce; rots of lettuce; and cercospora of beet greens, chard, and spinach.

General growing conditions like condensation, ground moisture and freeze/thaw damage were also noted during site visits. Scouting results and grower observations were discussed with growers at each visit.

Pest Control Demonstrations

Scouting data was compiled and trends were assessed immediately after each scouting run. Pest control was deemed necessary under the following conditions:

- Average number of aphids exceeded 1.0 aphid per leaf, or population was rising and expected to
exceed threshold before the next visit.
- Caterpillar or slug counts of more than 1 per plot
- Caterpillar and slug damage ratings of greater than 1.5, or on a rising trajectory

The need for pest control also factored in the overall pressure and prevalence of the pest in the house. For example, if a single weedy, excessively moist plot had a slug rating of 2 and the rest of the crop and house had no damage, then action would only be necessary in that isolated area and not the entire house. Time of year and temperature also affected the recommendation. Lepidopteran feeding will decrease in December, but they will survive the cold and feed heavily again in February. Bt sprays are most effective when temperatures are above 50F. To create effective season-long pest control, a more aggressive caterpillar control strategy was taken in the fall, since any population present in late November would be very difficult to control until late February.

Choice of control method was dependent on crop canopy, time of year, pest pressure/population size, and temperature (Table 3). All applications were made following product label directions. Frequency of application was informed by scouting and experience gained through this project.

Cultural factors also played a role in pest control and disease control. Wet, cool environments with poor airflow favor both slugs and disease. Opening up canopies by planting less densely, and improving weed control had real impacts on the losses caused by both. Cultural factors were included in pest control recommendations as appropriate.

Case-Study Teaching

Growers participating in the case-studies were informed of their pest pressures and population trends at or after each visit. Regular in-person and phone conversations engaged the growers in identifying areas for improvement and creating ways to incorporate pest management into their routine crop work. Growers were taught how to scout for each of the common pests, learned to distinguish slug from caterpillar damage and frass, and gained understanding of cultural control tactics. Regular conversations helped align grower loss estimates with staff damage ratings and action thresholds, allowing both parties to improve their pest management understanding and skill. Detailed data including pest populations and controls employed can be found in the annual case studies attached to this report.

Measuring Case-Study Knowledge, Skills, and Adoption

Cooperators received an end-of season survey that measured adoption of biological/biorational pest control strategies, planned adoption of pest control best management practices (BMPs), and pest management knowledge and skills. Questions were of open-ended, listing, likert, and checkbox types. Labor and work environment impacts were also assessed. Growers had an opportunity to provide feedback to project staff and suggestions for future research topics during this process. The survey was distributed online, with an option to fill out a paper form or go over the questions as an interview. Survey results were compiled and examined for each season.

At the end of the project, verification visits were paid to 17 of the 20 case study farms to document learning, adoption and impact. 3 farms did not participate due to exiting the farm, refusal and lack of relevance. The interview was based on the survey that the grower had completed in the year of their participation. Results were again compiled.

Broader Teaching, Outreach, and Adoption

Project staff shared findings with the broader high tunnel and farming communities through presentations at formal winter meetings, growing season crop walks, farmer-farmer discussion groups, and individual phone, email, and on-farm consultations. A number of print articles were written and a factsheet on aphid control in winter greens was created. Additionally, project staff shared what we learned with 61 Extension and NRCS staff from New York, the Great Lakes region, and Canada, which further extended the outreach and impact of this grant project.

A broader reaching online survey measuring grower knowledge and adoption of winter pest control best management practices was sent to 229 emails of program participants collected throughout this project. The survey was designed to correlate winter pest management program exposure with changes in knowledge, pest management, or economics. Results were cross tabulated and percentages calculated for knowledge, skill, and adoption.

Research results and discussion:

Results and Discussion/Milestones

  1. Educational meetings reach 150 growers; introduce economic benefits of cool season vegetable crops and biological control.- In January 2011 a session at the Empire State Fruit and Vegetable Expo reached 50 growers. In February 2011 a presentation at the Great Lakes Vegetable Working Group reached 30 extension professionals. A November 2011 presentation at the Cornell Cooperative Extension Ag In-service reached 15 extension professionals.
  2. 4 on-site grower trials (monitored bi-weekly), technician collects aphid numbers, aphid predation data. Over 4 winter seasons on 20 farms in 11 counties across New York State hosted on farm trials or case studies.
  3. 4 Farmers provide percent marketable (clean) crop, and yield in pounds. By the end of the project 20 farms provided this data.
  4. Above data used to narrow effective treatments promoted. Completed as part of ongoing project work with all cooperators.
  5. On-farm meetings at 2 collaborating farms demonstrate methods to 80 growers. 3 on farm meetings in Spring of 2012 drew 44 growers.

  1. Site visits to 15 entry-level Over 100 farms visits were completed by the project team, with at least 20% being entry-level growers.
  2. Continue on-site grower trials. This is a continuation of milestone # 2, completed with 20 farms hosting on 24 farm trials or case studies.
  3. On-farm meetings at 2 collaborating farms demonstrate methods to 60 growers- Winter/Spring of 2013 6 on-farm meetings with an attendance of 47 growers.
  4. Regional winter meetings present findings to 100 growers. -January 2012 attendance at NOFA-NY annual winter meeting and Empire State Fruit and Vegetable Expo is estimated at 175 both featured project related presentations.


  1. Statewide winter meeting reaches 40 growers. -December 4, 2013 35 growers attended the High Tunnel School - Winter Greens Production Day held in Batavia, NY. Similar meetings were held on December 9th in Paul Smiths and on December 13th in Voorheesville, NY reaching 80additional growers.
  2. On-farm meeting demonstrates methods to 40 growers.-December 4, 2013 35 growers attended a workshop and on-farm demonstration meeting in Kent, NY.
  3. Adoption surveys mailed to 200 growers contacted during the project. -Spring 2014 an online survey measuring grower knowledge and adoption of winter pest control best management practices was sent to 229 emails of program participants collected throughout this project
  4. Adoption verification via minimum of 20 farm visits.- 17 farms were visited by Spring 2014 to document learning, adoption and impact.



Participation Summary


Educational approach:

This project conducted 11 on-farm meetings, 7 formal educational seminars, and 3 professional development events with combined attendance of 516 people. Over 100 farm visits were made by project staff, 6 newsletter articles, Tweets and 1 aphid management factsheet were created.

In 2010 field meetings were held at 2 farms with an approximate total of 25 growers in attendance.

In 2011 a session at the Empire State Fruit and Vegetable Expo reached 50 growers. A presentation at the Great Lakes Vegetable Working Group reached 30 extension professionals. A presentation at the Cornell Cooperative Extension Ag In-service reached 15 extension professionals. A 4-part series of articles in the VedgeEdge weekly newsletter reached over 250 readers.

Winter meetings were held at a cooperating farm in Cattaraugus County on March 5 2012 with 12 people attending, Allegany County on April 3, 2012 with 20 people attending, and the Essex County on March 27 with 12 people in attendance. Presentations on the project were made at the NOFA-NY annual winter meeting January 21, Empire State Fruit and Vegetable Expo January 26, a Season Extension workshop held in conjunction with Alfred State College March 5 and a Northern New York Winter Greens workshop in Willsboro, NY on March 27. Total attendance at these three meetings was approximately 200. Both the NOFA-NY annual winter meeting and Empire State Fruit and Vegetable.

2013- The following meetings contained on farm demonstrations, education on winter pest management techniques, or discussion of adopting farmers’ experiences:

March 8 Busti, NY-8 growers
May 8 Allegany, NY - 5 growers
June 12 Almond, NY – 8 growers

July 12 Hector, NY – 5 growers
October 9 Little Valley, NY – 8 growers
October 15 Canandaigua, NY– 13 growers

Additionally, 35 people attended the High Tunnel School - Winter Greens Production Day held in Batavia, NY on December 4. The intensive school had a heavy pest management focus: two presentations related to preventative and reactive pest management, grower experiences with pest management, an on farm tour at a 2012-2013 cooperating farm (Kent, NY), and an in-field scouting lesson. Participants included established greens farms, farms considering winter production, urban farming and school gardening program coordinators, and research and extension professionals.

Similar meetings were held on December 9th in Paul Smiths eand on December 13th in Voorheesville, NY. These meetings reached an additional 80 growers in the northern and eastern regions of the state. Structural design and siting influences on diseases of winter grown greens were among the topics at these meetings.

2014-A professional development event was held for 30 NRCS and CCE staff on pests management in winter high tunnels, including presentations from cooperating Canticle Farm in Allegany, NY on June 4 and 5 in Penn Yan, NY.

2013-14 was a very difficult year for winter greens growers across the Northeast due to extended cloudy periods and low temperatures. These common struggles prompted a peer-to-peer conference titled Frozen Ground, a gathering of over 20 experienced winter greens growers in Fairlee, VT. Results from this project were shared by the PI at this conference. Presentations can be found at

We appreciated the comments of a Clinton Co. grower, who said to us “Keep up the training, there’s always more to learn”.

No milestones

Additional Project Outcomes

Project outcomes:

Impacts of Results/Outcomes

Performance target: 20 high tunnel growers to adopt biological or biorational control methods to manage pests of cool season greens gaining $2000 of marketable product per season.

Performance target met when case study results and broader survey results are combined. 24 winter greens high tunnel growers adopted biological or biorational control methods to manage pests with an average increase in revenue of $2465.13. One survey indicated 61% of increased revenue was attributable to increased awareness and skills in natural pest management.

Impact related comments from program participants

“In addition to increasing my knowledge and skill sets in the subject area – winter greens pest management – the regular contact with CCE project person gave me access to a great resource who was always willing to discuss all ag related questions. It was a great and wide ranging learning experience for me.” – Allegany Co. grower

“Less aphid pressure means quicker harvest, fewer culls, faster wash/processing.” – Allegany Co. grower

“Participating in this project has made me take my blinders off. Slowing down enough to emphasize pest management, reprioritizing tasks to get management things done in a timely fashion, helped lead to work environment improvements on my farm…. There is an increased quantity of high quality produce.” – Cattaraugus Co. grower

“Has been a huge help. Before we scouted, but didn’t really do anything about it, weren’t being proactive.” – Ontario Co. grower

Economic Analysis

Economic Analysis

The case study farms were asked to track yield and losses due to pests and disease as a part of their work in the project. They reported these numbers, along with harvest window, market outlet types and frequency of sales in their end of season surveys. The same information was collected at the end of project verification interview, to allow comparisons from the year of cooperation to the most recent year of greens production. These numbers were used to calculate income, losses due to pests and disease, and changes from year to year in income and pest losses.   Values were standardized to a “$/1000 sq. ft. of growing space/week of marketing” unit in order to compare changes across farms and to compute average changes in economic impact.

The broader economic impact to winter greens growers was measured through the online survey. Respondents were asked if they had sold winter greens for more than one season. This established a baseline for comparison and avoided skewing results by including the dramatic increases in sales due to new production. Respondents were then asked to report on any increases they experienced in number of weeks of harvest, number of market outlets, or revenue. Responses were averaged and reported.


Farms were asked to report on revenue at the end of each season they participated. Growers tracked yield throughout the winter harvests, making note of marketable and unmarketable yield. These numbers were collected for the year before and the year of their participation and used to generate change in farm revenue figures.

For the 2010-2011 and 2011-2012 winter seasons, growers identified the total marketable and unmarketable yield per 1000 sq.ft. of growing space and the average price per pound received at market. The average change in winter greens revenue was $573.69 for the 5 farms completing surveys in 2010-2011. However, two farms reported no change in revenue. The average for farms reporting any financial change that year was $956.15.

The 2011-2012 season was a challenging one to collect economic data. One farm suffered a killing freeze before the majority of the crop was marketed and had no information to provide. The remaining two farms did report yield information, but site visits were limited by an unanticipated extended family-leave of the primary field staff. Trials were carried out in the fall, but scouting and pest control work throughout the season was limited. Although lacking robust pest control data, the economic information collected on those two farms was deemed appropriate for use as a baseline to compare against their 2012-2013 year.

2012 saw a refocus and reinvigoration of data tracking. A major change was made in the way case-study economic information was gathered and analyzed, starting in the 2012-2013 season. Experience gained the previous two years taught staff that the change in season-long revenue per farm was influenced by many factors. Planting date, area planted, weather, and disease, among others, have significant impact on the profitability of a winter greens crop. To separate financial changes due to other causes from those due to improved pest control practices, two modifications were made.

The first was asking the growers to include produce culled after harvest and produce left unharvested in their assessment of unmarketable yield. They were also asked what percent of the total unmarketable yield was due to pests, and what percent was due to diseases, freezing, or other causes of loss.

Data analysis up to this date was insensitive to financial impacts due to changes in weeks of marketing, planting area, and cause of loss. There was no way to compare impact between farms without excess non-project variability. A standardized unit was needed. The unit selected was $ of revenue/1000 sq.ft. of production area/week of marketing. Baseline and participation year data for 2012-13 and 2013-14 were computed on both a season-long, unstandardized basis and on the standardized $/1000 sq. ft./week unit. Changes in overall revenue and changes in the amount of revenue lost due to pest pressure were then calculated for both years, combined.

In the last two seasons, 10 of the 15 farms provided sufficient information to complete a statistical analysis. Of the 5 not providing enough information, two farms did not complete the survey, two had only 1 year of information due to freeze losses, and 1 did not track yield due to farm staff turn-over.

On average, these 10 farms reported a season-long, overall change in winter greens revenue of $-432.82. They reported decrease in losses due to pests of $711.70. This means that had farms not improved their pest control by participating in this project, they would have suffered an average revenue loss of $1146.52. On a season-long basis, improved pest control help farms make up for revenue loss caused by weather, increased disease pressure, and late planting dates.

On a standardized unit basis, farms made $11.07/1000 sq.ft./week more than they did before improving pest control. 61.1% of that increase, or $6.76/1000 sq.ft./week was due directly to improved pest control. The remainder of the difference was attributable to increased planting area and changes in weeks of harvest/marketing.   Using the standardized unit allowed for direct comparison of the effect of pest control and weeks of harvest on revenue between farms. It is also a better comparison of year-to-year changes on farms that altered their production area.

A farm using a standardized unit during the season can track performance against weeks of production to determine when they are making or losing money, and due to what causes. For example, one grower was reported a standardized increase in losses due to pests of $4.69/week, due largely to voles. By decreasing his weeks of harvest from 26 to 17, he was able to market a similar quantity of crop and minimize losses to an unmanageable pest population. In the end, he posted a standardized gain of $28.71/week by making that decision.

Looking at these numbers, it becomes possible to assess the ratio of marketable:unmarketable yield. On this scale, a 1:1 ratio means that 50% of the crop was unmarketable. On average, the ratio changed from 4.77:1 to 5.26:1. Again, 61.1% of that improvement was due to improved pest control. The ratio is most useful in quantifying the impact of non-pest pressures. One farm ratio dropped from 25:1 to 3.5:1 due to a severe infestation of chickweed that impeded harvest and smothered regrowth. Another farm’s ratio dropped from 17.7:1 to 1.6:1 due to a hard freeze.

The project found that certain pests are more difficult to control than others and can cause disproportionate economic losses. One farm lost $1660.00 per season, with at least 75% of that due to spinach crown mite, a pest that is currently without any effective controls. On a standardized unit basis, spinach crown mite cost the farm $7.13/week and was the primary driver of the farm’s $-6.64 revenue change/week for the length of the season.

Finally, disease was as great a cause of an economic loss as insect and mite pests. Combining all seasons and sites, disease accounted for 26.1% of farm losses. Before pest control improved, pests caused 35.5% of losses and disease caused 37.0%. Once pest control improved, disease accounted for 22.8% of losses, compared to 14.7% due to pests. Growers report disease as being much harder to manage than pest pressure.

Economic Results from Online Survey of High Tunnel Winter Greens Growers

The online survey to the broader high tunnel contact list contained an economics and pest management section. Of those responding, 20 grew winter greens and 12 had sold for at least two seasons, making economic comparison questions relevant. 11 of 12 said they got pest management information from Cornell Cooperative Extension and all 12 indicated exposure to winter greens pest management programming. Of the 12 growers, 9 (75%) had experienced an increase in cool season marketing.

Those 9 growers were asked if they had experienced an increase in revenue (thousands of dollars), weeks of harvest, or number of market outlets over the past five years. Five years was chosen since that was the working timeframe of this project. Growers responded by sliding a bar on 0-12 scale. The average increase for those 9 respondents was $6,110, 9.2 weeks of marketing, and 2.2 market outlets.

Farmer Adoption

Case-Study Farms

Each annual report includes a summary of that year’s case study farms. Grower adoption of specific control and cultural practices are outlined in those reports for the year(s) that they participated. The final verification visit survey measured adoption by asking the four following questions. Responses of the 16 farms completing the survey are shown below.   All 16 growers responded to each question.

  1. Are you managing for winter pests? Winter diseases? How? (open-ended responses)

Scouting and Reactive Practices
Scouting & sticky monitoring cards: 13
Iron phosphate bait: 7
Bt: 6
Biologicals: 3
Mycotrol-O: 1
Deadline Bullets (slug bait): 1
Harvest of infested area to contain problem: 1

Cultural and Proactive Practices:
Improved ventilation/airflow: 6
Weed control: 5
Good sanitation practices: 3
Resistant variety selection: 3
Rotation: 3
Interplant repellent herbs: 1

The adoption of scouting and pest monitoring devices is key to the successful treatment of a pest problem. Project staff trained growers in scouting techniques and taught them how to interpret their scouting numbers. One grower noted “I’ve gotten a lot better at scouting and then asking what things are.” In addition to the self-reporting, site visits and conversations with growers indicate that all are including some form of pest monitoring in their winter greens production.

Many growers adopted biological/biorational controls because they had a positive experience with them as case-study site. Most farms are also using proactive, cultural best management practices (BMPs). For example, by improving airflow a grower decreases the environmental favorability for slugs and reduces his disease risk.

Adopting proactive practices and biologicals reduce pesticide use. When pest populations did require pesticide treatment, growers chose to use “softer” materials in all but one case. Scouting increased the success of these controls because pest populations were detected early, and the population had not yet exceeded the management capacity of the softer materials or biological insects.

  1. What do you look for when selecting a variety for winter production?(open-ended responses)

Pest/Disease Control Factors
Downy mildew (disease) resistance: 14
Hardiness: 8
Varieties for winter production: 5

Business Factors
Market acceptance: 5
Fits production schedule: 2
Economics of the crop: 1

The majority of growers sited varietal resistance as the number one consideration for winter production. The major diseases they were concerned about were downy mildew of brassicas; downy mildew of spinach; downy mildew of lettuce; rots of lettuce; and cercospora of beet greens, chard, and spinach. Their concern with disease is completely valid. Economic work undertaken by this project shows that disease and pests caused equal crop losses before adoption of pest control BMPs (see Economic Analysis section of this report). After pest control BMP adoption, diseases became the number one biotic cause of crop loss.

Hardiness and varietal suitability for winter production also help in pest and disease management. Vigorous varieties are better able to fight off disease and to remain productive longer under initial pest populations. Hardiness in winter tunnel production can be thought of as tolerance to cold stress. Our observation was that cold stressed plants are more susceptible to diseases and pests. Damaged from the freeze/thaw cycle made plants prone to bacterial rots. In addition to variety selection planting date and temperatures in mid-to-late fall can influence winter hardiness. Growers who were avoided over-sized crops entering December and January saw less damage.


  1. How do you practice warm season pest management?

Scouting and Reactive Controls
Scouting: 10
Organic/soft pesticides: 8
Beneficials: 5
Conventional pesticides: 2

Proactive Cultural Controls
Weed control: 7
Crop rotation: 5
Row cover: 3
Creating beneficial habitat: 2

This project has shown that a house with a low pest population going into winter greens production is significantly easier to keep under control than one with an established pest population. Thus much of our education and scouting stressed management of pest populations in a summer crop.

Several growers also listed sanitation techniques that they employ in and around the tunnel. Special attention should be paid to transplant house sanitation. Several times in this project winter greens transplants became infected with pests in the starter house before being transplanted into a tunnel. One grower highlighted several sanitation steps he now takes in the transplant house, including scouting, removal of old or stock plants, and removal of old potting soil.

The fourth question asked growers to rate their agreement with statements gauging pest management knowledge and skill, and current and planned implementation. The second to last statement includes general changes in knowledge or behavior related to participation and captures the tangential benefits of involvement on areas like disease control and cultural management. The final statement gauges the impact of project work.

  1. Please rate your agreement with the following statements: (16 responses to each statement-See Table 4. attached)

Grower comments also indicated adoption of pest control. One grower that received the parasitoid wasp mix for aphid control said he learned about the use of beneficials and how they fit into pest management in a high tunnel. He also learned how to identify pests by feeding damage and address the problem. This was evident when he recently began a conversation with project staff about how he planned to use iron phosphate bait to control a slug outbreak in this year’s crop.

Another grower with a history of disease troubles reported that he improved his disease control using techniques taught by project staff. He reduced disease by increasing air flow, improving sanitation, selecting better variety selection; and increasing weed control, which contributed to having more greens at market.

General Adoption

The broader online survey attracted 18 commercial vegetable growers that raise winter greens. These respondents were asked questions related to their pest management knowledge, practices, and changes in pest pressure over the project duration. Respondents were also asked where they received pest management information and asked whether they had had exposure to project related programming or written materials during this time.

The 18 had an average of 3.375 years of winter greens growing experience. 5 respondents were growing greens before this project began. All 18 had exposure to pest management programming, 15 through multiple methods.

Leaf lettuce, spinach, and leafy Asian greens were identified as the most important crops. Respondents identified slugs, aphids and caterpillars as their most common pest problems.

17 people completed the cool season pest management section of the survey. All of them practiced sanitation, ventilation, rotation, and weed management as pest/disease control strategies. None reported using calendar sprays to control pests, and only two sometimes used broad spectrum pesticides.   For the calendar sprays and broad spectrum pesticides, the number adopting the practice in the past five years reflects the number that previously used these practices but have stopped or reduced their reliance on these methods. (See attached Table 5).

16 people proactively scouted their crop, 15 selected pest tolerant crops, 14 controlled pests in summer plantings, and 11 used biological control or soft pesticides; all pest management practices emphasized in project meetings and articles.

There was a particular interest in use of biological and softer pesticides. The 11 growers that adopted softer pest control methods used controls as outlined below. Parasitoid/parasitic wasps and ladybeetles were most commonly used. In total, 16 different uses were reported for aphid controlling products, 7 for caterpillars, and 5 for slugs. (See attached Table 6).

Finally, the 17 respondents were asked to assess changes in their pest management knowledge and skills. 12 felt that “they know more now about cool season pest management than they did in the past” and 9 “find that their cool season pest control is better now than in the past”. (See attached Table 7).

Adoption comments

“I learned how to identify pests by feeding damage and address the problem.” – Monroe Co. grower

“Improved disease control through increased air flow, sanitation, variety selection, and weed control as a part of working with project staff contributes to having more greens at market.” – Cattaraugus Co. grower

“I’ve gotten a lot better at scouting and then asking what things are.” – Livingston Co. grower

“Control inside of a week and a half, never saw anything for the rest of the year. Had less than 3% of seconds. Freaking amazing.” – Yates Co. grower

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

One of the greatest challenges we found in winter greens production is the inherent variability of yields year-to-year. Different planting dates and fall/winter temperatures can cause greens to grow excessively prior to the coldest part of the winter or leave crops undersized. In our experience winter growing may be more susceptible to these swings than crops during warmer months. As growth is so slow during this time, there is little opportunity for plants to ‘make-up’ lost time due to late planting or waterlogged soils.

Research needs were gathered at the peer-to-peer learning event Frozen Ground in August 2014. As listed by growers, top priorities included:

  • Disease resistant varieties (Fusarium and Cladysporium in spinach)
  • Fertilizer and nutrient management in winter greens
  • Chickweed control
  • Temperature and light management through the use of row covers and light diffusing plastic and alternative heat sources
  • Standardized planting date recommendations and benchmarking for business tracking.

A complete list and details can be found at

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.