Optimizing Film, Fabric, and Root Zone Heating Combinations in Fall-to-Spring High Tunnel Vegetable Production

An increasing number of growers look to harvest and market vegetables grown in high tunnels fall to spring. Selling freshly harvested material (e.g., leafy, root, and other crops) from roughly October through April appeals to some farmers but it also raises many production-related questions in practice. Many of these questions relate to the use of plastic films, fabric row covers, and supplemental heating (including of the root zone). Questions such as which ones to use, when, for how long, under what conditions, and in what combination are common. The Vegetable Production Systems Lab has completed research in this area for more than fifteen years, cooperating with farmers often and using high tunnels at OARDC in Wooster which range in size, approach (conventional, organic; flat ground, raised beds), and other characteristics. Findings from these experiments have been summarized in publications (including VegNet) and during programs around the Eastern U.S. Our newest experiment was initiated on Sept 23 and includes the 20 wood-framed raised beds shown here, each seeded to either Scarlet Nantes carrot, Outredgeous lettuce, or Ovation greens (Brassica) mix from Johnnys Selected Seeds. This experiment will examine the influence of daily (8 am – 5 pm) root zone heating (accomplished with electric cables placed approx. 7 inches below the soil surface) in combination with vented plastic film row cover on crop development, yield, and quality. Vented plastic film covers all twenty plots (beds) while daily root zone heating occurs in ten of the twenty plots. Root zone heating will be discontinued at six weeks after seeding but the film will remain in place through final harvest in December. These treatments were chosen partly because two findings have been common in previous research. First, crops (e.g., lettuce, Brassica greens, carrot) and varieties have responded very differently to the use of film, fabric, and root zone heating — whether used alone or in various combinations. The same trend appears to be underway given the relative sizes of the crops shown in the pictures below (taken 10/9/21; carrot at top, Ovation Brassica mix in middle, lettuce at bottom). Second, in this experiment, we are very interested in root zone heating as a supplement to the above-ground heating that occurs with film in place and is typically pronounced September to early November and late January through March. Finally, temperature and relative humidity are recorded in each plot every five minutes, allowing us to describe treatment effects on these conditions very reliably. The sensor unit shown in the bottom-most picture below also relays the temperature and relative humidity readings to the “cloud,” allowing us to see the numbers in near real-time. This battery- and solar-powered Hobolink monitoring and reporting system from Onset Computer Corporation has been in place for more than two years and has greatly enhanced the efficiency and effectiveness of our high tunnel ventilation management across the ten tunnels in our program.

 

Wayne County IPM Notes From August 9 – 13

Vegetable Crops

Squash vine borer damaged plants.

This week brought about many sightings of squash vine borer larva. The adult squash vine borer moths were actively flying and lay eggs about a month ago. We are now seeing plants that are declining in health and when inspected further, are oozing frass and have stems that look shredded. When we split the stem of these plants, in nearly every instance, we found at least one, if not several squash vine borer larvae. Unfortunately, there is nothing that can be done to reverse such severe damage.

A large squash vine borer found feeding in a pumpkin plant.

Flea beetles are feeding on young cabbage and broccoli, and the cabbage worm butterflies are finding their way into these plantings as well. We are starting to see some damage in peppers from the European corn borer and expect the ECB and CEW numbers in the traps to increase in the next week or so.

Small Fruit and Orchards

As apples and peaches are harvested, do not let your guard down on the late season generations of codling moth and oriental fruit moth. This past week was another week of rising codling moth numbers, and consistent oriental fruit moth catches, although the oriental fruit moth numbers have not gone back over threshold.

Grapes damaged by grape berry moth larvae.

Grapes are starting to ripen, and as the season progresses, we are still finding consistent trap catches of grape berry moth. Although it may be too late for some varieties, you may still be able to protect later maturing varieties with a treatment for grape berry moth.

Notes from the Pumpkin Patch

Pumpkin Field Day – August 26

Pumpkin field day flyer

We are less than 13 days away from the 2021 in-person pumpkin field day on August 26 at the Western Ag Research Station (7721 S. Charleston Pike, S. Charleston). We will have two hours of presentations plus time for growers to roam the plots and see what interests them, including the powdery mildew fungicide trial, pumpkin and squash hybrid trial, and weed control plots.

The field day starts promptly at 5:30 PM where we will have Dr. Aaron Wilson from OSU talking about weather impacts on pumpkin production and Tony Dobbels reviewing a weed screen plot with 10 herbicide treatment combinations of Reflex, Sandea, Dual Magnum and Strategy. For diseases, we were very fortunate to pry Dr. Dan Egel from Purdue University to speak about disease control in pumpkins. Jim Jasinski will briefly cover the pumpkin and squash trial and powdery mildew fungicide trial. After the presentations the participants will be allowed to move around the plots. The field day will end at 7:30 PM.

Pre-registration is a must for this event so please use this link.
https://osu.az1.qualtrics.com/jfe/form/SV_7WnQLmG3bcyQWc6

Cut-off for pre-registration will be Aug. 24. No walk in registration will be possible. Social distancing and mask wearing might be required for the outdoor event so come prepared. No beverages will be provided so bring your own.

Weed Control Video on IPM YouTube

Tony Dobbels talks about weed control in pumpkins and squash

For growers who are unsatisfied with their early and mid-season weed control in pumpkin and squash,  take 15 minutes and check out this new pre-emergent herbicide video narrated by Tony Dobbels, Department of Horticulture and Crop Science. In the video, Tony reviews 10 herbicide treatments and combinations of  Sandea, Dual Magnum, Strategy and Reflex (currently under a 24c label) and gives his thoughts on their level of control and fit for overall pumpkin and squash production. Watch the video here: https://youtu.be/NmSX4FqK7T4

Powdery Mildew Beginning to Roll
After what seemed like a slower than average start to the powdery mildew season (at least at the research station), leaves in the untreated checks have been climbing to between 50-75% coverage. Be sure to treat on a 7-10 days schedule and use proper FRAC number rotation to reduce the incidence of fungicide insensitivity. Sally Miller’s article on July 10 (https://u.osu.edu/vegnetnews/2021/07/10/addendum-more-powdery-mildew-fungicides-for-cucurbits/) is a great resource to what has been working lately in Ohio and is a must read as we approach the mid point of the disease management season.

Pumpkin Insects Report
For the most part squash vine borer has died down for the season. I saw some extensive damage in the Hardin County crop walk a few weeks back in zucchini but haven’t seen it in any of my pumpkin or squash plantings at the station, although I have been actively catching adults until about two weeks ago.

Cucumber beetles are still hanging out in the flowers but as we approach 100% orange in some of our trials, fewer and fewer flowers are being produced so I expect a switch soon to possible rind feeding. If you are in a similar situation, keep an eye on flower production and where the beetles are actively feeding to avoid rind damage which could lower market quality.

Mating squash bugs.

So that leaves squash bugs as the only insect I see at the station beginning to increase fairly steadily, with many egg masses being detected on leaves, followed by gray nymphs typically aggregated together and eventually larger brown adults. These pests have sucking mouth parts and can feed extensively on the petioles, vines and fruit, sometimes causing collapse. If there are over one egg mass per planting, treatment of the emerged nymphs is easier than waiting for them to become adults. Only treat if necessary to avoid aphid explosions with their accompanying honey dew and black sooty mold on leaves and fruit.

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.