Wayne County IPM Notes from July 19 – 23

Vegetable Crops

Powdery mildew found on a cucurbit plant in a Wayne County field.

The Vegetable Pathology Lab at OARDC has confirmed several more cases of downy mildew, on both cucumbers and cantaloupe. It is important to take steps to either protect your crop or stop the spread of any ongoing infections. Powdery mildew is also spreading rapidly through the area. Although some heavy rains may have slowed its spread, favorable conditions have led to some fields rapidly becoming infected.

Flea beetles feeding on young green cabbage plants.

Bacterial diseases continue to spread in pepper and tomato plantings. Pay close attention to these crops in particular, and make sure that you are taking the necessary precautions so as to not spread bacterial diseases. Bacteria can be spread from plant to plant via clothing, equipment, or animals. More from APS

Flea beetles are feeding heavily on recently planted cole crops, which left uncontrolled can cause stunted and underperforming plants. Another insect we have seen quite a few of is the squash vine borer. Although these are not typically going to harm large numbers of plants, they can still be a nuisance, especially in smaller plantings.

Small Fruit and Orchards

 This week we found our first incidence of scab in apples. While this was only an isolated find on a few leaves, it is a good reminder to take some time to scout your apple trees and look for any signs of scab. Oriental fruit moth numbers were significantly above threshold again this week. Japanese beetles were also

Severe damage from Japanese beetles feeding on the foliage of apple trees.

still feeding heavily in many of the fruit crops we scout. Spotted wing drosophila are still being found in all of our traps, and for anyone with small fruit in the area, it is recommended that you treat for SWD.

Optimizing Vegetable Fertilizer Programs

Recent farm visits, questions from growers, and observations of research plots have me thinking about nitrogen and other fertilizer programs for vegetable crops grown in open fields and high tunnels for fresh and processing markets. What are optimal ranges for each production situation, which factors influence optimal rates most significantly, and what steps can growers and others take to identify optimal rates for each farm and planting?

Ranges currently recognized as optimal are published in numerous guides, handbooks, and other resources. The Midwest Vegetable Production Guide for Commercial Growers, Southeast Vegetable Production Handbook, Mid-Atlantic Commercial Vegetable Production Recommendations, New England Vegetable Management Guide, and references available from Cornell (e.g., https://cropandpestguides.cce.cornell.edu/) and other universities are helpful in Ohio and the region. The publications provide operating fertilizer application targets and tips on how to reach them. Targets in the publications are the best available benchmarks. However, it is best to think of them as not fixed in stone and as needing to be validated for individual cropping situations. On-farm validation (adjustment by trial and error) using published, research-based and other reliable benchmarks as starting points saves time, money, and headache.

Indeed, since production conditions change continuously and research-based recommendations require years to develop, evaluating fertilizer programs (material, rate, timing, placement) often is good practice. Like effective crop protection programs, fertilizer ones are not static, they need to be updated as weather patterns, varieties, rotations, fertilizer materials and their costs, and other factors change. Observe crops now and through the remainder of the season and ask if you are convinced their fertilizer programs are optimal. If you aren’t convinced, consider experimenting carefully.

Experiments are most effective when they account for factors that tend to influence their outcomes most significantly and consistently. To refresh my memory on these factors, especially nitrogen application rate effects on watermelon and other Cucurbit crops, I looked at extension resources referenced above and reports from research completed in the U.S. and other countries. I was also very pleased to hear from Ohio growers on the same topic.

That input pointed to the following seven factors as most likely to shape optimal fertilizer, especially nitrogen, application rates for individual farms, soils, crops, and plantings.
1. Soil type and condition. Sandy, loam, or clayey? Organic matter level? Have a prominent plow layer or other condition affecting drainage, etc? Fertilizer programs must be calibrated to soil type and condition since they influence many facets of nutrient availability at any one time.
2. Fertilizer application approach. For example, will fertigation be used? Fertilizer application approaches influence which materials are used, when and where they are applied, and their likely efficiency.
3. Precipitation and irrigation. Soil moisture management is a very large percentage of nutrient management. Are the irrigation and fertilizer programs in sync? Is rainfall cooperating? Can the program be adjusted for weather?
4. Variety(ies). Shifting market expectations (e.g., large to personal-size melon) may have implications for the fertilizer program. Similarly, the program may also need to be adjusted to maximize gains from using grafted planting stock because rootstocks may differ in, for example, their abilities to obtain nutrients and water.
5. Cultural practices. Production on plastic-covered raised beds versus the flat. Standard versus strip- or reduced tillage approach. Row and plant spacings (plant populations). These and other factors are consistently mentioned as factors shaping the four R’s (material, rate, timing, placement) of all fertilizer programs. The fertilizer program may need to be tweaked if any of these factors are changed.
6. Crop growth stage. Especially important for fruiting vegetables, including Cucurbit and Solanaceous crops. Nitrogen and other macro- and micronutrient levels influence many aspects of crop biology directly impacting (fruit) yield and quality from seeding/transplanting to harvest. Metering nutrient availability by crop stage is a proven, essential tactic in soilless greenhouse production. The same level of control is impossible in soil-based field or high tunnel production; however, a realistic application of the principle can be beneficial in both systems.
7. Nutrient credits. There is often little need to apply what is already there. Basing planned applications on current, reliable soil test data is a cornerstone of successful, efficient, cost-effective fertilizer programs.

Finally, setting optimistic but realistic yields goals, especially for non-vegetable rotation crops, if any, is also beneficial. Realistic yield goals help avoid significantly under- or over-applying fertilizer, regardless of crop. Avoiding such deficiencies and excesses enhances the overall return on investments in the current and subsequent crops.

Partnerships, Teamwork, and Persistence Bring New Potato Varieties

Hundreds of new, promising, numbered (unnamed) potato genotypes are evaluated at research station and farm sites each year. Ohio State is one of many institutions involved. In 2021, we are evaluating more than 100 numbered selections from four breeding programs against seven standard industry varieties. The same evaluation techniques we use can be employed by individual vegetable farms.

High-performing varieties are just one of the core raw materials for vegetable production, which also relies on water, mined or manufactured inputs and equipment, and the know-how to use all of them. Whether formal or informal, variety evaluation is essential for individual growers and the vegetable industry. Since now is when differences among varieties of individual crops begin to show themselves on farms and research stations, it’s a good time to discuss traits and processes used to evaluate varieties.

When we evaluate genotypes of potato being considered for naming and release as varieties, we score plant maturity and record total and marketable yield and more than ten tuber characteristics for each entry (e.g., tuber size and shape, skin color and texture, flesh color, eye depth, incidence of internal defects, and specific gravity and chip color). Collaborators in other states evaluate the same genotypes for pest and disease resistance, crop tolerance to heat stress, storage effects on tuber quality, and tuber cooking quality and sensory properties. So, like for other vegetables, developing potato varieties requires teamwork.

Background on the Variety Development Process

Experimental genotypes originate in public-sector breeding programs based at universities and the USDA. In fact, although varieties developed by private companies (e.g., major processors) contribute significantly, the U.S. potato industry (especially the fresh/tablestock and chip sectors) has long relied on varieties developed in the public sector. Public-sector varieties are developed by large teams led by universities, USDA, and/or state industry associations or organizations and account for most of the available varieties, acreage, and value of production.

Whether public or private, variety development teams include breeders/geneticists, agronomists/horticulturalists, plant pathologists, entomologists, food scientists, farmers, processors, and people with expertise in related areas.

Potato varieties are named, released, and made available for commercial use only after years of comprehensive, widespread testing, beginning with just a few plants and concluding at farm scale. Once released, varieties support processing (i.e., chip, fry), fresh market/tablestock, and/or breeding programs. The varieties ‘Atlantic’ (released in 1976), ‘Dark Red Norland’ (1957), ‘Katahdin’ (1932), ‘Kennebec’ (1948), ‘Red LaSoda’ (1953), ‘Superior’ (1962), and ‘Yukon Gold’ (1981) are just a few examples of public-sector varieties that have been planted to many thousands of acres over decades of production. Varieties like these set the bar for and/or are found in the “family trees” of newer, increasingly popular varieties.

Still, markets, production conditions, and industry factors change continuously. Therefore, variety development must be ongoing and once-popular varieties are eventually displaced by new, more farmer-, processor-, and consumer-friendly ones. The process is designed to enhance industry success and consumer satisfaction.

Evaluation is nearly continuous since sites are located throughout the U.S. and the process begins before planting and ends long after harvest. Groups based in the East, Midwest/Upper Midwest, West and Pacific Northwest, and South often coordinate the work. Ohio State and Ohio farmers and processors have participated annually for more than fifty years. We emphasize the evaluation of genotypes originating in eight breeding programs and with potential value in fresh and chip markets and have contributed to the release of multiple varieties used in Ohio and elsewhere.

Sharing Results

Data from our 2021 trials will be summarized in a report available at https://u.osu.edu/vegprolab/technical-reports/ with data from 2020 and previous years available at https://neproject.medius.re/trials/potato/ne1731 and https://neproject.medius.re/. Later, we will join team members from Maine, New York, Pennsylvania, North Carolina, Virginia, Florida, and USDA and industry partners to discuss evaluation outcomes and begin selecting new entries and others to be evaluated again or dropped from the program. With information reflecting variety or experimental selection performance in the field and on the plate, the breeder and team have key information when making the thumb-up/thumb-down decision on each entry.

Still, for all crops, the performance of each variety (or experimental genotype) hinges on how it is managed, the know-how allowing growers to get the most from each variety. Planting and harvest dates, plant populations (spacings), irrigation and fertility programs, etc. influence variety performance and, therefore, whether a grower will select the variety again. So far, potato genotype evaluations at Ohio State have been completed without irrigation and this approach has clearly affected tuber yield and quality. We are rethinking this approach and look forward to speaking with vegetable and potato growers about their use of irrigation.

Wayne County IPM Notes From the Week of June 21 – 25

 

Imported cabbage worm eggs in the red circles and a recently hatched caterpillar circled in yellow.

Vegetable Crops

            Imported cabbage worm butterflies are laying a lot of eggs on cole crops. It is important to scout the crops for the eggs as well as the larvae, in order to have a better grasp on when the larvae are hatching and causing damage. This will also help ensure efficient and timely insecticide applications.

Aphids are continuing to be present in many of the vegetable crops that our IPM program scouts,

Thrips feeding in on onion leaves in the center of the plant.

however, we are finding a lot of beneficial insects that are feeding on the aphids and helping to either maintain or eliminate populations. Japanese beetles also are present now in many of the crops in our area.

This week was also the first week that we really noticed an increase in thrips in onion plants. As the leaves get larger and offer more shelter for the thrips, the populations are able to multiply rapidly.

Some sweet corn in the area is tasseling, silking and in some cases, nearing harvest. We have noted some European Corn Borer feeding in tassels. If 10% of silking plants are damaged by ECB, a treatment is warranted. In some fields, this threshold was met, and growers started on a spray program for their tasseling and silking corn.

Small Fruit and Orchards

Aphids in the apple trees continued to be the main pest this week. We found more clusters of wooly apple aphids, which are now working their way out onto the new shoots and green growth. Our trap counts for OFM remain well below threshold.

OFM traps in peach blocks were also well below threshold, however, we did see an increase in the trap counts of Greater and Lesser Peach Tree Borer.

Strawberry season is winding down. Our SWD traps in strawberry patches yielded 0 SWD. Harvest is starting in some area blueberry and bramble patches. Grape clusters are developing nicely and starting to put on some size.

Wayne County IPM Notes From the Week of June 14-18

Vegetable Crops

            This growing season, so far, has been all about the bugs. We have not had a huge amount of disease pressure

Squash bug eggs on summer squash.

on the vegetable crops in our area. We have, however, continued to find more insects impacting local crops.

Newly spotted insect pests this week included Japanese Beetles, thrips, and squash bugs. The Japanese Beetles were found in silking sweet corn, the thrips are being found in onions and the squash bugs are being found laying eggs in summer squash plantings.

 

Japanese Beetle found in a sweet corn stand.

In green beans we are still seeing a light population of potato leaf hoppers and a few bean leaf beetles feeding here and there. Cucurbits still have some cucumber beetles feeding, as well as some aphids. Aphids are not picky about which crops they are in, as we continue to find them in a variety of crops, including peppers and tomatoes. Both eggplant and potatoes are dealing with flea beetle and Colorado potato beetle. The Colorado potato beetle larva are becoming very prolific in some areas and causing significant defoliation. Cole crops, while also dealing with pressure from flea beetle, are now seeing an increase in activity from the imported cabbage worm caterpillar.

Small Fruit and Orchards

Aphids and mites are being found in fruit trees, primarily apple trees. This week, we began to find European red mites, green apple aphids and wooly apple aphids. Trap counts for CM in apples and OFM in peaches were all below threshold, with many traps reporting zeros.

The biggest update in our pest outlook in small fruit was not an insect, instead it involved birds. There was bird damage being found in strawberries, as well as in blueberry areas where the berries are starting to color. Some growers are using netting to exclude the birds from blueberry plantings. This is a lot of work but saves a lot of berries from being damaged.

Recognize and Mitigate Crop Heat Stress

Recent conditions in some areas (soaked soil, fog- and dew-filled mornings, high daytime humidity) can give a different impression about the season so far than weather data at https://www.oardc.ohio-state.edu/weather1/ and various forecasts. Temperature, rainfall, and other data are collected around the clock at OSU vegetable (and other) research sites in Fremont, Celeryville, Wooster, and Piketon and have been for decades. So far in 2021, these four locations have accumulated less precipitation and more growing degree days (GDD) than their historical averages. Also, climate and weather authorities reported on June 11 that the Upper Midwest, including Ohio, is set to experience hot, droughty conditions. Most agree that a dry year is less problematic than a wet one — provided irrigation is possible. However, it can be difficult for vegetable growers to escape the unwanted effects of excessively high temperatures. A way to separate potentially minor, moderate, and severe heat stress, example effects of moderate-severe heat stress, and main strategies for mitigating heat stress during production are summarized below.

Five Major Factors Influencing Whether Heat Stress is Minor, Moderate, or Severe

  1. Crop and variety (sensitivity 1). All crops and varieties have a range of temperature in which they perform best. A crop’s genetic past (i.e., heritage/Center of Origin) and level of improvement through breeding matter. Individual crops and varieties are thought or proven to be relatively heat tolerant or intolerant.
  2. Timing (sensitivity 2). When high temperatures occur in the crop cycle is key. Crop plants can tolerate high temperatures more reliably at some stages than others. Even relatively tolerant varieties can be impacted by temporary spikes in temperature at the “wrong” time.
  3. Intensity. The extent to which actual temperatures exceed the crop’s and variety’s optimal range is important … 5 degrees? 15 degrees?
  4. Duration. The length of time the temperature was consistently above optimal. Short periods of intense stress can be problematic although the effects of prolonged moderate stress typically accumulate.
  5. Mitigation: were steps taken to lessen the stress?

Combinations of these five factors represent common scenarios. For example, for vegetables for which pollination is required, excessively high temperatures lasting only hours can disrupt pollination or trigger flower or fruit drop or interruptions in normal developmental patterns. The result can be loss of a “set” (dip in production) and/or malformed or misshapen units to be harvested (e.g., pods, fruits, roots, stems, leaves, tubers). Longer periods of above-optimal temperatures can speed (e.g., bolting) or delay (e.g., prolonged vegetative state) maturity depending on the crop and when they occur in the crop cycle. Heat stress is also implicated as a contributing factor in fruit ripening and physiological disorders (e.g., blossom-end rot). Above-optimal temperatures can also trigger changes in the chemical composition of plant tissues, possibly affecting the color and/or taste of marketable units. Similarly, prevailing temperatures can influence a crop’s tolerance to typical inputs and protectants.

Irrigation and shading are among the most common strategies for mitigating the effects of excessively high temperatures in field and high tunnel vegetable production. Irrigation is essential for the obvious reason that evapotranspiration is the crop’s primary means of cooling itself. A warm period or season calls for the best irrigation (scheduling) practices, not just pouring water on because, as we know, excessive irrigation (soil moisture) disrupts water uptake, compounding the heat stress problem. Circumstances allow some growers to shade the crop (e.g., in high tunnels) as they attempt to reduce the temperature around it.

At this time, 2021 has not earned the label as a “hot or heat stress” year. Let’s hope that remains true even as we remain aware of factors contributing to heat stress and ways of addressing it. In addition to proper irrigation, shading (if possible), and careful application of inputs and protectants, consider tracking variety performance closely to aid in variety selection going forward.

Wayne County IPM Program Scouting Notes From the Week of June 1- June 4

Vegetable Crops

Cucumber beetle feeding on the foliage of a summer squash plant.

Insects continue to be the main headline in the vegetable crops in our area. Of greatest concern is the cucumber beetle. The populations continue to increase in number and the efficacy of seed treatments or in-furrow applied insecticide starts to decline 4-6 weeks after the seed germinates or after the insecticide is applied. This means that more of the beetles are feeding without being affected by the insecticide. Be sure to scout cucurbit crops frequently and carefully to get accurate counts of the beetles. The thresholds for cucumber beetles are as follows: Cotyledon stage – .5 beetles per plant, 2-4 leaf stage – 1 beetle per plant, greater than 4 leaves – 3 beetles per plant. Limiting the amount of feeding that cucumber beetles do will also limit the amount of bacterial wilt occurring in these plantings. Do be cognizant of the plants that are in bloom and limit your spraying to a time when it will be least impactful on the pollinators.

 

Colorado potato beetle larva feeding on a potato plant. Tommy Becker photo.

Other insects that were spotted this week include Colorado Potato Beetle larvae and imported cabbage worms. Both of these pests can cause significant damage in their respective crops when left unchecked. Flea beetles also continue to feed on plantings of cole crops, preferring young transplants versus older, more established plantings, although both should be inspected for beetles.

Sweet corn plantings are growing quickly and some plantings that were done into plastic mulch and covered this spring already have a few tassels poking out. Overall, there has been no major concerns in the sweet corn plantings so far, however, do your best to keep up on weed control. Weeds such as bindweed, thistle, and ragweed can not only compete for resources, but can also make harvest difficult and may serve as refuge locations for insect pests to retreat to.

Small Fruit and Orchards

We are beginning to enter a critical period for managing diseases in grapes. This period, which extends from immediate pre-bloom through four to five weeks post bloom, is a critical time to control fruit infections by the pathogens which cause black rot, powdery mildew, and downy mildew. According to the 2021-2022 Midwest Fruit Pest Management Guide, the fruit of the most commonly planted varieties becomes resistant to infection by these diseases by four to five weeks after bloom.

In strawberry plantings we are seeing a lot of green fruit and in some locations, harvest is beginning to ramp up. Overall, there have been very few concerns in the

Blueberries starting to enter the “fruit coloring” stage.

strawberries to this point, with just a few slugs here and there and a spotting of powdery mildew on a few plants. Powdery mildew is managed by spraying either pre-bloom or during the early bloom through bloom stage.

Other small fruit like blueberries and brambles look to have a heavy fruit set this year. Blueberries are beginning to get some color to them, and the blackberry and raspberries are either in bloom or in fruit development.

In apple and peach orchards, the fruit are noticeably starting to increase in size. We are finding some aphids in apple trees, feeding on the leaves and new shoots. In peaches, we did find a few instances of powdery mildew affecting the fruit. Trap counts for OFM and CM were under threshold in all of our traps this week. The counts are down after last week with several orchards above threshold for CM and OFM counts.

Wayne County IPM Notes from the Week of May 17th – May 21st, 2021

Vegetable Crops

             As we move into warmer temperatures, it would be best to remove row covers from field planted crops in the interest of pollination and reducing heat stress. In crops that do not need pollinated such as cole crops, the row cover can serve as an insect barrier and prevent early infestation from the Imported Cabbageworm. Crops such as summer squash, cucumbers and tomatoes

Flea beetles feeding on a recently transplanted brassica plant.

all need to be uncovered sooner than later to avoid poor pollination and subsequently, poor fruit set.

Hot weather can also be problematic when transplanting into black plastic. The black plastic can become very hot and planting a young, tender transplant into the plastic on a hot, sunny day can cause a significant amount of stress, burns on the leaves and stems and in some cases, death of the transplant. Try to plant in the evenings, as temperatures cool down or on cloudy, cooler days.

Colorado Potato Beetle adults on a potato plant.

In the last week we have seen an explosion of flea beetle in cole crops, and the Colorado potato beetles have begun to make their way into potato plantings. Frequent scouting and monitoring of these insect pests is extremely important. Large populations on young plants can stunt their growth and reduce yields. Conditions have been ideal for rapid population increases, hence the need for frequent scouting. An interesting insect problem we observed was a planting of cole crops where the roots of some plants were being destroyed by ants. In most cases, as you turn on your irrigation lines under plastic, it will drive the ants elsewhere.

Generally speaking, disease pressure has been very low in vegetable crops to this point. We have observed some early blight in a tomato high tunnel, as well as blossom end rot in high tunnel tomatoes.

Small Fruit and Orchards

            Apples and peaches are both reaching fruit development. There was significant growth and change in the size of the fruit over the past week. Out of all of

Strawberry blooms with black centers, damaged by freezing temperatures, alongside healthy blooms.

the orchard traps that we have out, we caught 1 OFM and 1 CM. We began to find aphids in apple orchards. The feeding was evident by curling leaves and shoots.

Blueberries are in petal fall and are setting fruit. Raspberries are getting ready to bloom and overall seem to be coming along just fine.

Grape bud that had been damaged due to freezing temperatures now showing secondary growth. Tommy Becker photo.

Strawberry varieties that were early to bloom, and left uncovered, likely suffered heavy bloom loss due to the freezing temperatures that we experienced. Some early blooming varieties had very few, if any, healthy looking blooms. Many plants have put on new blooms, which are very easy to distinguish from the frosted blooms. Early varieties of plasticulutre strawberries that were covered and protected from the cold are setting fruit and beginning to ripen and may even be in harvest. We are not finding any thrips at this time. Unfortunately, we are finding a lot of slugs in strawberry plants and on the berries.

Currently, grapes are now past the bud burst stage, as most are at the 4-8” shoot stage.  We are beginning to see where grape buds that had been damaged due to freezing temperatures are putting out secondary buds and shoot growth, which is very promising

Grower Survey to Assess Herbicide Drift Damage in the North Central U.S.

A special project group of the North Central Integrated Pest Management (IPM) Center wants to learn about your concerns and experiences with herbicide drift. The group is surveying growers of fruits, vegetables, and other specialty crops in the upper Midwest.

To truly understand the frequency, severity, and economic impact of herbicide drift on specialty crops, we need to hear from growers: growers who have experienced drift damage, growers who can share their concerns around this issue, and even growers who have not dealt with drift but who grow sensitive crops in drift-prone regions. Survey responses are needed to establish herbicide drift as a serious economic and regulatory concern in Ohio and across our region.

Please complete the survey at go.osu.edu/drift21.

Who should take this survey?
The study is for commercial growers of fruits, vegetables, and other specialty crops in IA, IL, IN, KS, MI, MN, MO, ND, NE, OH, SD, or WI. Even if you have never experienced herbicide damage, we would still like to hear from you if you grow specialty crops in one of these states.

Why is this survey necessary?
Dicamba and 2,4-D drift damage has made headlines in recent years, but no study to-date has attempted to quantify the overall impact drift has on the specialty crop industry. While all states have a way for growers to file a drift complaint, the process and requirements are inconsistent and may involve time and information that a grower does not have. In most states, for instance, the source of the drift must be identified. Research has found that dicamba and 2,4-D both have the potential to travel for miles in specific weather conditions, making source identification difficult.

What good will this survey do?
This study is designed to assess the potential and actual frequency of drift damage, along with the severity and economic impact of such damage. The survey includes questions on grower awareness, experience, actions, and decisions related to herbicide drift and drift-risk management. The responses will help establish needs for research on drift mechanisms, prevention, and remediation; and/or the need to review current policy and reporting requirements.

How long will it take?
The survey takes 5-20 minutes to complete, depending on your experience with drift damage.

How will this data be shared?
Summarized survey data will be shared broadly with regulatory agencies, university educators and researchers, agricultural policy makers, grower support organizations, and the general public using news articles, report summaries, and peer-reviewed journal articles. While this study is administered by The Ohio State University, it was planned in partnership with industry experts across the region who will assist with sharing results. Participants may also request a copy of the study summary.

How will my data be used and protected?
Your privacy is important. No individual survey data will be released or shared beyond the limited group of project staff. The survey questions and procedures have been reviewed by the institutional review board at The Ohio State University and are designed to protect your data and identity. Additional details on privacy and confidentiality are provided at the beginning of the survey.

How can I learn more?
The North Central IPM Center’s special project group created a series of fact sheets on herbicide drift especially for specialty crop growers. The series includes: Overview of Dicamba and 2,4-D Drift Issues, Frequently Asked Questions, Preparing for Drift Damage, and Responding to Drift Damage. Fact sheets and more information about our special project group and study are available at go.osu.edu/ipm-drift.

This study is facilitated by The Ohio State University and is funded by the USDA National Institute of Food and Agriculture through agreement 2018-70006-28884.This study is being conducted in cooperation with regional universities and non-profit grower organizations, including Ohio State Extension.

Soil Sampling and Analysis for High Tunnel Production

Installing a stationary high tunnel (HT) is a significant, long-term commitment to the parcel of soil beneath it, especially if the crops will grow directly in that soil. Maintaining, and preferably enhancing, the health, quality, or productivity of that soil for as long as possible should be a high priority beginning at HT installation.

Soils in HTs are less well understood than uncovered soils in “open sky”/open field production. However, the HT farming, extension-research, and industry communities are aware that HT soils are prone to specific issues and require specific care to remain commercially viable. These issues and preventative or reclamation tactics are the subject of much research and extension. Therefore, HT growers are encouraged to stay tuned for more information, including on how they can participate directly in identifying concerns and developing solutions. Examples of concerns and working solutions were summarized in a recent presentation (https://www.youtube.com/watch?v=XpUl0IwaDFI). Choosing one concern, in a summary of a presentation given at the 2013 New England Fruit and Vegetable Conference (https://newenglandvfc.org/sites/newenglandvfc.org/files/content/proceedings2013/Hoskins%20High%20Tunnel.pdf), Bruce Hoskins of the University of Maine’s Analytical Lab and Soil Testing Service mentions that the buildup of nutrient salts over time is “one of the most common problems in a continuously covered HT system,” that HT soil management can be similar to “irrigated desert production in the west and southwest,” and that growers familiar with open-field production can “fail to realize this potential problem or take steps to remediate it.” He also mentions that nitrate may carryover from one HT crop cycle to the next more readily than in open field production.

We heard from Bruce Hoskins and John Spargo during recent conversations about HT soil management. They direct soil testing and analytical labs at the University of Maine (https://umaine.edu/soiltestinglab/) and Penn State University (https://agsci.psu.edu/aasl), respectively. Each of these labs receives soil samples from hundreds of HT growers (conventional, organic) each year and have been actively helping improve soil management recommendations and cropping outcomes for HT growers. They have been joined in that work by others, including farmers, across the Northeast and Mid-Atlantic regions for years.

Take-aways from these recent conversations include that routine soil testing is essential, along with accounting for potential nutrient salt buildup when collecting soil samples. Normally, samplers: 1) use a soil probe or spade to retrieve a column of soil about twelve inches deep, 2) drop the soil in a bucket, 3) repeat the process one or more times from other areas, 4) mix the soil in the bucket, and 5) submit a portion of it for analysis. Listening to testing and other experts, the best approach appears to include “stratified” sampling; that is, submitting samples taken from 0-4 inches deep (upper layer of the rooting zone) separately from samples taken from four inches and deeper (lower layer of the rooting zone). Salts tend to accumulate in upper layers, especially if soil is heavy-textured and irrigation is frequent but brief. So, standard “mixed” samples may either: (a) underestimate salt levels in upper layers of soil experienced by roots of transplants and more mature plants or (b) overestimate salt levels if samples include only the upper level. Stratified sampling, mindful that soil characteristics can change with depth, equips growers and others with information to better manage HT soils. Regarding the costs of soil testing, especially of stratified samples, input from soil testing labs suggests that few of the growers they work with mention it as a significant concern. Instead, most growers appear to have done their math and concluded that soil analysis offers a significant return on investment, given that its cost is more than offset by gains in crop yield and quality in the current and subsequent years.