The OSU Extension Fruit & Vegetable Report is written and published collectively by OSU Extension staff across the state.

Vegetables

Onion plants are off to a quick start this spring. As the plants quickly add leaves, this provides ample opportunity for onion thrips to get started. Scouting for onion thrips is incredibly important early in the season as they become increasingly more difficult to manage as the season progresses and the onion plants become larger and more heavily foliated. Scouting for thrips involves carefully pulling apart onion leaves near the neck and examining down into the crotch of the leaves. On a sunny day, thrips will react to the sudden exposure of sunlight by moving downward, deeper into the leaf collar. As you evaluate management decisions, also be aware that heavy rains may provide assistance in management of onion thrips as the rain washes the thrips out of the leaves or drowns the insect.

Photo by Frank Becker, OSU Extension.

Colorado potato beetles are emerging and becoming active in potato plantings. The adults are very difficult to control with pesticide applications. Control is more effective when applied to newly hatched larvae. Please reference the Midwest Vegetable Production Guide to find effective products for management of the Colorado Potato Beetle. 

Colorado potato beetle larva feeding on potato foliage. Photo by Chris Galbraith, OSU Extension. 

Squash and cucumber continue to be seeded. Striped cucumber beetles are out. As an important reminder, early season control of cucumber beetle is critically important in preventing bacterial wilt in your cucurbit plantings. The threshold for beetles while plants are in the cotyledon stage is 0.5 beetles per plant. The threshold for beetles at the 3-4 leaf stage is 1-2 beetles per plant, and for plants with 4 or more leaves, 3-5 beetles per plant. Scouting during the morning or evening will give you the best results, as beetles are often difficult to find during the heat of the day. Recent chewing and feeding damage can also be indicative of beetle activity. This can be differentiated from “old” feeding damage as the older damage will look scabbed over, but the recent feeding will appear as a “wet” wound.

Cabbage maggot, caterpillar, and swede midge damage is being observed in cole crops. Reports of some early season flea beetle activity have led to some growers already making applications to limit damage to young cole crops. Flea beetle feeding can be scouted for by looking for “shot hole” style feeding patterns on the foliage of the plants. Early season feeding, especially on young transplants can significantly stunt the plants, and in some cases when feeding is severe enough, seedling death can occur. 

High tunnel tomatoes are fruiting and field tomatoes are being planted where growers can get into the fields. 2-4,D drift damage has been observed in some high tunnels. Powdery mildew and thrips are the main pest of concern in greenhouse tomatoes at this point in the season. 

Early blight and powdery mildew have both been found in high tunnel tomatoes. Powdery mildew, as the name describes looks like powdered sugar on the upper leaf surface. These symptoms can develop at any level of the plant.  Early blight, or Alternaria, has an alternating ring/bullseye like pattern, often with a yellow halo around the lesion. Early blight is most often first found on the older foliage near the bottom of the plant.  Please scout your high tunnel tomatoes frequently and thoroughly, especially early season to catch early season disease presence and hopefully prevent major impacts throughout the season. Please read fungicide labels carefully to make sure that the crop and disease are both listed on the label. Remember, the label is the law. 

Recently planted sweet corn is beginning to emerge. Slug damage is being observed, although not severe at this point. Now is also an important time to be checking sweet corn for black cutworm. Cutworms damage the pants by cutting the plant off at or slightly below the soil line, significantly stunting the plant or causing plant death. If infestation levels are high enough, stand loss can occur to the point of necessitating a replant. 

Fruit

With the mild winter, fruit, vegetable, and agronomic crops alike are getting a quick start in Ohio this year! It seems the pathogens got the memo as well as educators and specialists around the state are reporting an early onset of several diseases on fruit. One disease that we are seeing in orchards this spring is apple powdery mildew.

Powdery mildews are among one of the more recognizable diseases in our specialty crops and can have a significant impact. Some folks are probably familiar with the cucurbit powdery mildew that we find on the cucumbers, zucchini, and other cucurbit crops in our fields in gardens. Powdery mildews are host specific, so the powdery that we observe on apple trees will not lead to powdery mildew infections in our cucurbit crops. They are different species. Usually, we see cucurbit powdery mildew as we get further into summer, around July. That particular pathogen does not overwinter in Ohio and has to be blown in by the wind from areas where it can overwinter.

Apple powdery mildew is quite different, caused by the species Podosphaera leucotricha. Apple powdery mildew can overwinter in fruit buds that were infected in the previous season. Another interesting thing about powdery mildew is that while it does need a higher relative humidity, it does not require free water for development. Many of our other diseases do have that requirement. So, even in drier years, powdery mildew can still pose a challenge.

Powdery mildew is one of those diseases where when we scout, we can observe both the signs and symptoms of the disease. In other words, we can see both the physical evidence of the powdery (Sign: the white fungal growth) as well as the plants response to the infection (Symptom: stunted, crinkled leaves). The first thing you will likely see in spring is the white fuzzy or waxy appearance to the leaves. As the disease persists, leaves will become stunted, crinkled, and brittle. As the season goes on, the disease can spread to the twigs, stunting their growth, and potentially leading to dieback issues. In severe cases, symptoms can show up on fruit resulting in russetted apples.

Photos by Thomas Becker, OSU Extension.

Apple powdery mildew can be managed with some cultural integrated pest management tactics. One tactic is to plant varieties that are less susceptible or potentially resistant to powdery mildew. Another tactic is to plant and manage your trees to allow for good air movement and light penetration. This can lower the relative humidity around the trees and make it more difficult for the pathogen to get established. Chemical controls are also an option. If powdery is a persistent problem in your orchard, it may require the development of a good fungicide program to get adequate control. Contact your county extension educator, one of our state specialists, or reference the Midwest Fruit Pest Management Guide for current fungicide recommendations.

References:

•         Ohioline Apple Powdery Mildew Fact Sheet, https://ohioline.osu.edu/factsheet/plpath-fru-21
•         Powdery Mildews, Colorado State University Extension, https://extension.colostate.edu/topic-areas/yard-garden/powdery-mildews-2-902/
•         Apple Powdery Mildew, Washinton State University, https://treefruit.wsu.edu/apple-powdery-mildew/

Apples have progressed quickly in their development. Codling moth trap catches are high across the state. Insecticides to control first generation codling moth should be on to slow the second generation. Wooly Apple Aphids are on the move in the trees, as they move from the roots to the limbs. San Jose Scale is present as well and male flight has been observed in southern Ohio. Plum curculio damage present (petal fall applications are best to control infestations). Pear psylla adults active. 

Lacewing eggs hanging from branch. Lacewings are beneficial insects that feeds on aphids and other fruit & vegetable pests. Photo by Frank Becker, OSU Extension. 

Strawberries are ripening and some varieties are in harvest. Main pests at this point are slugs, spittlebugs and birds. Phytophthora leather rot and sun scald being observed in fruit. Brambles are blooming, blueberries setting fruit. 

For more information or if you have questions, please reach out to a member of the Fruit & Vegetable team or your county extension educator.

Produced by the Ohio Department of Health (ODH) Zoonotic Disease Program (ZDP).

Tis the season for ticks. I went for a stroll on a mowed path through a local meadow three days ago and picked up 3 American dog ticks about 6mm in size. I just came back from mountain biking and somehow picked up another American dog tick about 3mm in size. These arthropods are out in their habitat actively questing for a host to take a blood meal and maybe transmit a disease like Lyme, Rocky Mountain Spotted Fever, or several other serious pathogens. Read on and find out how to minimize your chance of being bitten.

Ohio now has five medically important ticks (Blacklegged, American dog, Asian longhorned, Lonestar and Gulf coast) that you might be exposed to on a daily basis depending on your location in the state and the kind of work you perform.

While most growers likely work from a tractor or within a planted field with little tick habitat, walking across grassy lanes between fields or walking through a cover cropped field can expose you several types of ticks (American Dog, Blacklegged, Lonestar). Working with livestock can expose you to other types of ticks (Asian longhorned, Gulf coast which has only been found on cattle).

Tim McDermott DVM featured in a tick prevention video.

Tim McDermott (DVM), Ohio State University Extension, created a video to highlight how to best reduce your chances of encountering ticks. Since growers need to be in the field to carry out their work, the option for staying out of those areas is not practical but Tim’s advice to consider making your clothes tick repellent via washing or sprays may be reasonable to try. Growers can also try clothing with repellent compounds impregnated into the fabric. No amount of prevention will remove all risk of ticks therefore frequent and thorough tick checks need to be part of a routine a few times a day, especially at night. Check out the short video and see what else Tim has to say about tick prevention.
https://youtu.be/GNc6hQdq9TE?si=Ki7hNy6juVtHibNP

How to remove ticks safely.

What happens if I find a tick on me, how do I remove it? Watch this short video for the safest way to remove ticks and avoid infection. Spoiler alert, this video does not include or recommend using lit matches, gasoline, kerosene, nail polish, duct tape or Vaseline as a safe removal method.
https://youtu.be/-hLHmKVWWAg?si=WV5XfknXEeIwrEsW

The five medically important ticks in Ohio.

How do I know what species of tick is on me? Concise summaries of all 5 medically important ticks in Ohio.
https://kx.osu.edu/bite/site/ticks

Want even more information about ticks in Ohio? Read this from the Ohio Department of Health.
https://odh.ohio.gov/know-our-programs/zoonotic-disease-program/diseases/tickborne-diseases

Striped cucumber beetle adult.

Mating squash bugs.

It’s mid May on the calendar but given how warm it is, it might seem more like late May or early June to some early season cucurbit pests. Based on our biweekly fruit and vegetable conference calls, no cucumber beetles or squash bugs have been reported in the state.

As growers begin to plan for direct seeding or transplanting, keep an eye out for striped cucumber beetles and squash bugs in particular.  Earliest planted fields will likely be infested soon after emergence or when placed in the field. For growers who purchased seed treated with FarMoreFI400, striped cucumber beetle populations should be controlled for 2-3 weeks. After this period if scouting reveals beetles in excess of plant stage threshold, foliar treatments are an option.  For growers who did not purchase systemic insecticide treated seed, remember to scout plants frequently in multiple parts of the field, edge and interior, and if the damage exceeds the following thresholds, consider treating with a foliar insecticide to knock these pests down. Foliar insecticide options can be found here: https://mwveguide.org/uploads/pdfs/Cucurbit-Crops_2023-12-20-141555_pieo.pdf

Systemic insecticide use and guidance on cucumber beetle thresholds based on crop type is listed in detail below based on an excerpt from an earlier VegNet article from J. Jasinski and C. Welty (2020).

Characteristic striped cucumber beetle feeding. FarMoreFI400 should prevent significant feeding and therefore limit bacterial wilt spread.

Systemic Insecticide Use Considerations
Seed treatments containing thiamethoxam (FarMore FI400, Cruiser) offer maximum protection against cucumber beetles and other pests for about 2 to 3 weeks after seedling emergence. Seed treatments offer little protection to transplanted crops. For transplants and direct-seeded plants over 3 weeks old, the concentration of insecticide from seed treatment is no longer strong enough to kill beetles but can still harm bees due to sublethal doses in the pollen and nectar. Treated seed should never be used in combination with at-plant soil drenches with flupyradifurone (Sivanto), imidacloprid (Admire or generics), or thiamethoxam (Platinum). At-plant soil drenches used alone, with non-treated seed, offer similar protection to treated seed for beetle control. Due to increased residues in nectar and pollen, in-furrow applications should be considered last and applied at the lowest recommended rate that provides control. Non-systemic foliar applications of insecticides can be used to control cucumber beetles if seed or in-furrow treatments were not used, or were ineffective. Once flowers are present, applications should be made in the evening when flowers are closed and bees are not actively foraging, which minimizes the risk to pollinators.

Thresholds range from 0.5 to 1 beetle per seedling, and 1 to 5 beetles per plant for plants after 4 leaf stage. The threshold for cantaloupe melons and cucumber is lower because these crops are susceptible to bacterial wilt, which is vectored by cucumber beetles. Pumpkin, squash, and watermelon have higher thresholds because these crops are less susceptible to bacterial wilt, but beetle feeding can occur on the fruit rind by both adult and larvae, causing marketable loss. Beetles found in pumpkin or squash flowers do not pose a risk to the plant but as flowering decreases, rind feeding may increase.

Pumpkin playlist on OSU IPM Video Library.

OSU IPM Video Library
Newly added this spring are additional resources in the OSU IPM Video Library. These resources help growers identify and manage all of the key cucurbit pests including striped cucumber beetle, squash bug and squash vine borer plus a new potential pest, the melonworm.

Videos on weed control, disease control (powdery mildew, plectosporium) and hybrid selection are also in this playlist collection.

https://www.youtube.com/playlist?list=PL0HRPaZDLHyH64oVLKdX5icKQFzqQ5nCA

The University of Kentucky Department of Plant Pathology has a great online vegetable diagnostic scouting guide.  Follow this link to check it out https://veggiescout.ca.uky.edu/