Determining the Biggest Bang for our (Time) Buck: Dealing with Fall Brassica Diseases in High Humidity Environments

Progress report for FNE22-030

Project Type: Farmer
Funds awarded in 2022: $14,198.00
Projected End Date: 06/30/2023
Grant Recipient: Hartwood Farm
Region: Northeast
State: New York
Project Leader:
Maryellen Sheehan
Hartwood Farm
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Project Information

Project Objectives:

The question we want to answer is what extra effort is worth putting into fall brassica disease management in damp years? Is it worth spraying after every storm, or are cultural changes or accepting some damage more cost effective? Our objectives include:

  1. Do cultural strategies impact the cost effectiveness of each spray regimen? Does a particular mix of cultural practices provide equal or better control of disease/bring higher yield?
  2. Is it cost effective to spray more frequently? Does the added time cost pay off through marketable product?
  3. Where is the sweet spot in the combination of practices/spray frequency with the highest net return?

We anticipate this trial will yield time and cost data on how many spray applications are most cost effective; which cultural controls most reduce disease; and how the two interact through measuring:

  • Cost of inputs for each treatment
  • Time each treatment takes
  • Plant health
  • Yield per treatment—marketable yield per bed foot in units/dollar value

Our hope is that combining these results into basic enterprise budgets will give our farm and others a starting point to improve fall brassica net profitability even as labor costs rise and late season growing conditions become more extreme.


Fall brassicas are a major crop family for diversified northeastern produce operations. They historically thrived in our region, and there are solid resources for general pest and disease management. However, these past years fall brassicas became more finicky. At our market, we’ve been the only grower with a consistent supply, but our cost to produce them skyrocketed, as a series of overlapping challenges has hammered our region and makes these former mainstay veggies increasingly difficult to profitably produce.

Our main disease local pressures match UVM’s 2019 survey: Alternaria and Black Rot most intensively, with lower pressure from downy/powdery mildews and head rot. The wetter, humid conditions of more intense late summer/fall weather raise these diseases’ pressure while reducing spray efficacy and opportunities to apply. Additionally, milder temperatures and later frosts encourage higher levels of insect pressure. Our immediate region experiences heavy flea beetle action (and intermittent Swede midge) making row covers essential to produce unblemished greens. Even using new covers each year, it’s apparent that sanitation alone doesn’t prevent row covers from trapping in moisture and fomenting disease. Without covers, flea beetles hit the brassicas hard, stressing out plants and creating their own openings for disease.

Because of declines in pollinator activity, most operators near us switched to spraying in late afternoon into dark, but even with adequate spray application, it’s still a tedious and quality of life reducing job for the end of the day, especially dealing with weight bags and row covers.

Finally, while more intensive spray management may work adequately to reduce the disease load, such time-consuming strategies threaten to make crop production unprofitable in northeastern states with high base labor costs. Farm employee costs in our community start at $15 to $17/hour, with an additional 25% mandated benefit and tax costs. This comes to net labor costs in the $20 to $25/hour range, which significantly alters the analysis of whether higher labor operations like spraying continue to make economic sense.

Essentially, farmers are pinched for the time to manage around an ever-growing roster of moisture-related diseases, and it’s unclear that the previous economics of management strategies remain valid. We’ve been trialing a range of cultural disease management solutions and spray mixes already on our farm, but we really want to take the time to dig in and measure to determine what is the most cost effective strategy. Is it worth killing ourselves to spray every few days, spending all that extra money on labor to get “perfect” fall crops, or is it more cost effective to maintain lower intensity management strategies and accept some level of damage and loss?

Our proposed solution is to set up a field trial to compare nine cultural disease management strategies that might further mitigate fall moisture-related plant disease against three levels of fungicide application frequency. We will measure disease pressure, input costs, labor costs, and harvest yield to examine interactions between treatments for any hint an economic sweet spot between cost, yield, and quality.

The heart of this trial is to produce a series of abbreviated enterprise budgets that help guide farmers to assess how much extra work we need to put in to increase the yields and quality of our brassicas in a rough year, and if at some point, that level of added labor becomes cost prohibitive.

Our main hoped for impact is to understand how to improve our end of the season farm productivity—do we need to prioritize spending more money for fall labor to keep spraying these crops, or is our time better spent spraying less and turning to cultural controls? Are brassicas still a profitable crop in super wet years? Is there a labor point where growing them no longer makes sense? Our goal is to spend the time to get a snapshot of what strategies other growers may want to try, as well as provide an update on budgeting for these added costs as wages increase in the region.

Finally, knowing where to most effectively reassign labor will improve quality of life for farmers. We don’t mind the hassle of crop maintenance and spraying, but only if it feels like our effort is effective to improve yields. Farming in these last wet falls, has been a slog, and we want to make sure we are at least slogging in a cost-effective manner.


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  • Crystal Stewart Courtens - Technical Advisor


Materials and methods:

This trial tests three levels of fungicide spraying frequency across nine difference cultural control zones to assess which interactions have highest net profitability.

The spray levels are high (weekly prophylactic applications), moderate (applications at 2 to 3 week intervals, and low (zero to one applications).

The cultural controls include three exclusion methods: row cover, ProtekNet, and no covers, normal crop spacing, wide crop spacing, bare soil aisles, landscape fabric aisles, block planting, and isolated plantings.

(See attached files for the trial matrix.)

There are four iterations of the trial, two plantings of fall transplanted large brassicas (a mix of broccoli, cabbage, cauliflower, kale, and kohlrabi) and two rounds of fall direct seeded small brassicas (mixed roots and greens).

Alternaria, black rot, downy and powdery mildews, and head rot are the disease culprits.

All four treatment zones are prepared by incorporating cover crops, vertical tillage after open fallow, and fertilizer (1500 to 2000 pounds/acre of Kreher’s 5-4-3) while tilling. Large brassica iterations have 4’ white plastic mulch and are transplanted using a Waterwheel. Small brassica iterations get bed formed prior to tillage, occulate under plastic tarps for three to eight weeks, and are seeded with a single row Jang.

Objective 1: Do cultural strategies impact the cost effectiveness of each spray regimen? Does a particular mix of cultural practices provide equal or better control of disease/bring higher yield?

We use these cultural controls already on our operation. Our goal here is to make extra time to test them individually against varying spray intensities to determine their relative impact.

  • Row covers—we need flea beetle exclusion, but suspect even lightweight covers reduce airflow and increase disease pressure. 10 of the 12 trial spray iterations include treatment zones with and without row cover after the initial two to three weeks of critical establishment. One Monnit temperature/humidity sensor will stay under a row cover zone for added data logging.
  • ProtekNet—our 2021 fall lettuce trial (for aster yellows control) showed better airflow, plant health, and yield over row cover. Additionally, we can spray through the netting without removal, unlike row cover. Given its price point, we are unsure if it’s worth using on lower value/wider spaced crops. For all trial iterations, a zone will be sealed under ProtekNet, with scouting and spraying happening through the netting. We hope to assess whether the added cost of the netting is offset by plant health and reduced application times. One Monnit temp/humidity sensor will stay under this zone.
  • Plant spacing. We transplant two rows per bed 24" apart, at in-row distances of 10”, 14”, 19”, 21”, or 25”. We direct seed three to four rows per bed top at .5” to 4” in-row spacing. For each spray iteration, one zone will have plants transplanted one step wider (at least 4” farther apart), or seeded at double typical spacing. We will assess if the cost to use extra space pays off in terms of disease control and yield.
  • Aisles—the 2 large brassica iterations each include an aisle section “mulched” with landscape fabric as opposed to bare ground to explore if the landscape fabric keeps water from splashing pathogens up from the soil. (Aisle landscape fabric is uneconomic for small brassicas.)
  • Isolation—for harvest convenience/irrigation, we plant fall crops in larger blocks. Starting in 2021, we began switching to a rotational system of smaller blocks of the most disease prone crops (in 2021, melons, cucumbers, and broccoli) to see if that reduced disease pressure. The cucurbits showed positive results, but the broccoli had mixed results (there were 20 inches of rain over five main growing weeks of the broccoli, which may have skewed results). For the large brassica iterations, each includes a zone with an isolated planting of one bed at a distance from any other brassicas. (Due to our tarping system, isolation is uneconomic for the small brassicas.)

Cultural controls data will be gathered in scouting reports, time/labor tracking, and any added time cost of installing/flipping each zone, and through tracking time and yields at harvest.

Objective Two: Is it cost effective to spray more frequently? Does the added time cost pay off through marketable product?

All zones are scouted at a 4 to 7 day interval from planting through harvest. Fungicides will be tank mixed as needed/compatible (with pesticides if needed for uncovered zones) and applied either via a tractor gun or backpack mist blower.

Our intent is not to trial individual product efficacy, but rather if overall frequency of fungicide application impacts the cultural controls. For fungicides, we will start off with preventative applications of biologicals like Double Nickle (Bacillus amyloliquefaciens), until scouting informs us to switch to rotating organic copper products like Cueva and Nordox with OSO (polyoxin D zinc salt). All applications include the sticker-spreader Miller Nu-Film P.

The three frequency intensities trialed across the cultural controls are:

  • High—every 4 to 7 days, and after every rainstorm over ¾”, from the week after planting until harvest
  • Moderate—every 14 to 21 days, down to 10 days if scouting suggests. Our current norm, largely due to weather conditions making additional applications feel like a waste of time.
  • Low/No Spray—zero to one timed spray application as scouting suggests. In these past years, because of rain, some fall brassicas received zero applications and still produced, which makes us question if any organic fungicide application is actually effective against very damp weather?

Data collection for these application intensities includes scouting logs—time taken and issues observed, spraying logs of time and mix rates, and the relative costs of pesticide inputs across treatments.

Objective Three: Where is the sweet spot in the combination of practices/spray frequency with the highest net return?

To find the balance between effort and cost of varying fungicide application frequencies across cultural disease management strategies, we compare the efficacy of spray frequencies versus the labor costs of spraying and installing cultural controls, using the lens of marketable product yields.

  • Data collection tools include: scouting logs, spray logs, time logs, and harvest and sales logs, kept and assessed through our Airtable database.
  • Costs measured include: inputs for each treatment including in-kind and project-purchased inputs, measured over the baseline costs of production.
  • How many extra work hours does it take to install or remove each treatment zone per row foot? This will be recorded at planting using timers and averaged over the treatment zones.
  • Additional time each treatment takes over baseline for:
    • Scouting on 4 to 7 day intervals, including time to move rock bags and row covers
    • Spraying, including time mixing and cleaning the tank and managing covers, assigned to each treatment
    • Time to harvest/harvest variations over treatment zones, recorded by the harvest crew. For consistency, a single individual will be in charge of harvesting to each specific crop throughout the trial to most accurately capture any relative impacts of treatments on harvest speed.
  • Plant health and what diseases show up where will be noted on the scouting sheets. Any confusing foliar samples we will consult with our technical advisor and/or send to the Cornell plant disease diagnostic clinic.
  • Yield per treatment—marketable yield per bed foot in units and dollars, recorded at harvest or in the wash/pack line, is the essential measurement metric to balance labor and input costs against.
Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary:

Education/outreach description:

We are currently working on written outreach materials! We plan to submit proposed articles over the next months.

We planned on hosting a fall field day at the farm, but all got Covid the week before the scheduled tour and were not able to recuperate and reschedule in time due to ongoing health issues--we did reach out individually to interested farmers that had been planning to attend.


Learning Outcomes

8 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:

We are still in process on disseminating the results of this study, so anticipate KASA reaching more farmers!

Our goal was to assess:

  1. Do cultural strategies impact the cost effectiveness of each spray regimen? Does a particular mix of cultural practices provide equal or better control of disease/bring higher yield?
  2. Is it cost effective to spray more frequently? Does the added time cost pay off through marketable product?
  3. Where is the sweet spot in the combination of practices/spray frequency with the highest net return?

Our results were all over the place with mostly weaker correlations in the data.

We realized in part this was due to having too many experimental variables and moving parts, and in part due to outside variables (of a drought, and then everyone on the farm getting Covid right at the peak two weeks of the experiment).

In particular, we began to observe midway through the study that field location (especially relative to soil water retention and previous brassica plantings), variety selection, and timing was playing more of a factor in the trial than the many factors we were studiously measuring!

We are still assessing our data to see if there's any clear results that we can draw, but our initial results indicate:

1. Do cultural strategies impact the cost effectiveness of each spray regimen? Does a particular mix of cultural practices provide equal or better control of disease/bring higher yield?

  • This was the area where the data was really unclear. We did not see clear efficacy of any products against Alternaria (and had minimal black rot, thanks to the dry summer). It was definitely faster to spray on iterations without row cover, but we found the row cover easier to manage than the netting (thanks to it being wider, cheaper so we weren't paranoid about damaging it, and something we have more practice at handling).
  • On a cost basis, the more expensive netting does not necessarily pay for itself relative to row cover, even factoring in that the row cover is only used once and the netting multiple times. However, it was unclear if this result was because the netting itself is less effective, or because the row cover we use covers 3 beds at a time (rather than 1 with the netting), thus reducing labor management costs.
  • Also on a cost/unit basis, open uncovered trials did not perform terribly, as long as the variety selection was a shorter season cultivar, and there were reasonable numbers of spray applications. However, open/uncovered beds did reduce overall yield, and should thus be further assessed. Open plantings generally outperformed netting on a cost/unit basis, while netting performed better on a total yield basis.
  • Landscape fabric increases yield, but it also increases costs/unit and should be assessed on a case by case basis. In truly dreadful disease pressure situations, landscape fabric did allow a meager harvest to be taken out (but it's not clear that it was cost effective)

2. Is it cost effective to spray more frequently? Does the added time cost pay off through marketable product?

Yes, but only a very weak correlation.

We saw strong reductions in pest numbers using Entrust (spinosad), even in the zone with very high pest pressure. However, we saw very weak correlation between spraying more frequent fungicides and higher yield of marketable product. We felt like there was more impact from variety selection and timing than from organic fungicides.

3. Where is the sweet spot in the combination of practices/spray frequency with the highest net return?

We are still looking at the data to see if further patterns emerge, but are leaning towards continuing with the landscape fabric and row cover combo as our preferred system (this was already the system we are using). However, we plan on removing row covers 2 to 4 weeks earlier than in the past, and significantly increasing our spray frequency for pests after the covers come off.

We also feel like we need to do more trials next year on fungicide efficacy, reexamine our varietal selection, and look at timing impacts (with very early and very late plantings both doing better than main season fall plantings). None of the organic fungicides performed for us this season once the alternaria started.

In terms of bigger systemic changes, we are considering the economic impact of either stopping fall transplanted brassica production entirely, or dropping our organic certification for these specific crops, as all the data this year made it clear that they are hit or miss to break even on.

Project Outcomes

6 Farmers changed or adopted a practice
2 New working collaborations
Project outcomes:

We are still assessing our season, but participating in this trial definitely had an impact on our farm operations for the future.

First of all, it stimulated discussions among our wider farm crew about the temporal and financial sustainability of diversified organic production (say for a CSA like ours). 2022's growing season was brutal financially with the increase in fuel and supply costs, and the first year where we started hearing from customers that they were reducing their food spending costs on produce.

Keeping such tight data made us better overall at time tracking, but also made us question the value of some of our actions, amendments, and crops. Is it worth trying to be organic in a high moisture environment when the customer wants nice looking product, but the efficacy of organic fungicides is questionable? When thrown to our members, the answer to this question - "Do you want your fall broccoli so bad you are willing for us to drop certification to guarantee it's good enough to eat" was all over the board. 

What we realized is that we don't want to live in suspense (and cannot afford the risk of) some of these high popularity, loss leader crops. Even in a good year, our loss rates are high due to disease. As much as we and our customers love these crops, our conclusion from this project is to adjust our fall crop mix to focus on more reliable crops and varieties (sprouting cauliflower, for instance, did great in all trial zones). This was made especially clear when our direct seeded trial zone cost less than $.10 per unit and the large brassica zones ranged from $.50 to $2/unit.

Assessment of Project Approach and Areas of Further Study:

We realized half way through the study that our trial had way too many variables. We tracked most of them through the course of the trial, but did drop tracking one variable (the wider plant spacing) when it became clear that more airflow wasn't impacting disease prevalence. This project definitely was a refresher for us in experimental design, especially in how difficult it is to manage variables when all of the zones have such a diverse mix of crops! We also switched from managing our data with AirTable to using paper forms, as we didn't want folks to have to use personal electronics in wet and dirty environments. This was likely a mistake and created a mountain of end of season data entry (that we just barely finished, hence the temporary nature of this report!).

We did answer the questions we started with, but those answers were somewhat inconclusive. Some of the general results we listed in the Learning Outcomes section, and we are still hashing the 2022 year (and data) to see if there are any more solid conclusions we can draw. But our main methodological lesson was to reduce the number of variables as much as possible, even if that shrinks down trial zones!

We plan to run a new round of trials next season based on these results, specifically digging into:

  • Trialing potential replacement crops to broccoli, specifically direct seeded single cut sprouting broccoli varieties.
  • Trialing with disease resistance as our main goal - looking to smaller seed houses and ones in wetter regions to see if we can source better resistance.
  • New fungicide combos, specifically limiting them to a 2 product rotation (max) so that we can see efficacy (and lack thereof) more clearly. 
  • Continuing time trials to identify which crop applications make most sense for landscape fabric on aisles. It definitely reduced disease and made moving bags and scouting/spraying easier, but it also has high time installation costs.
  • Seeing if we can modify the proteknet by sewing landscape fabric strips to the edges. While we like the reusability and higher strength of this material, it was narrow and difficult to keep plants from touching it (where pests could lay eggs through the netting), and we struggled with weeds and mud getting stuck where the weave touched the ground and ripping it. We have purchased lighter weight landscape fabric and plan to see if we can fabricate a solution that might combine two products that work (landscape fabric and netting) but that have high hassle costs.

While our data was not tightly conclusive, it did in general support the combo of actions we were already using on our farm - a mix of row cover and landscape fabric. The two main changes we plan to make for future seasons are to remove the covers significantly earlier than we did in the past, and to spray more frequently for pests (and continue to seek a fungicide that works!).

One of our unspoken goals on the farm is to move away from using plastics as it becomes possible, and this trial gave us a stronger framework to assess the relative merits of using agricultural fabrics (plastics) in the field, and a roadmap to consider to moving forward to reduce plastic use of row covers and netting (if we can get our spray application timing down and cut out the more fragile crops from our crop mix).

We had a few wider big-picture farm conclusions come out of this trial, including:

  • Our realization that it would improve our farm functioning and bottom line to drop some of our more iffy crops and move to growing fewer crops overall, even if we have considerable market demand for the dropped crops.
  • Juggling all these variables over just a fraction of our field operations really was eye-opening on our operational complexity for all the staff at the farm. As a result of the process to realize this, and the challenge of continuing to juggle all our crops and this study while knocked down for weeks with Covid, made us realize that our farm would be financially stronger if we moved away from a single-farm CSA to something more flexible and collaborative in the future.
  • We have been certified or followed organic practices for over twenty years. However, we are questioning the sustainability of organic approaches in high-moisture environments, given the current varieties available. We are continue to stay organic, but are starting to consider pulling a field out of certification to trial higher efficacy products that need fewer applications.

While our results from this trial were not very conclusive, we did feel like the process was important for us to have solid metrics to look at our operation. We plan to finish assessing our season and trial results in the next month, and share our conclusions more widely by March. We have started to reach out to other trials on organic fungicide efficacy in brassicas to see their results as well.

We feel that diversified smaller farms might benefit from these results, especially those who like us are juggling a number of market outlets and crop mixes. As a CSA-first farm, we primarily look at the whole-farm mix of income and expenses. Digging into this trial really exposed some losses that we have been trying to overcome by spending more time and energy on those crops, when it seems that the better response may be to cut and replace those crops. This can be an uncomfortable conversation, but we feel like a stronger operation going into 2023 having had it.

More results coming soon!


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.