OSU Extension Bi-Weekly Fruit & Vegetable Report– August 2nd, 2023

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

View a recording of the OSU Extension Bi-Weekly Fruit & Vegetable Report below:

Crop updates


Cole Crops

  Flea beetles are always a difficult foe in brassica plantings since they are often hard to scout for and can leave large amounts of damage in relatively short time frames. In research performed in 2022 by Dr. Ashley Leach, it was found that pyrethroids (e.g., Bifenture EC, Hero) and anthranilic diamides (e.g., Harvanta) performed best to control flea beetle populations and damage. However, if you frequently struggle with flea beetles, consider using their biology against them. You can plant a super tasty preferred brassica (turnip greens) which may keep them away from your primary crop. Alternatively, you can also plant other brassicas (like Kale) that aren’t preferred by flea beetles and can often take a high amount of damage. Often, flea beetles are a problem earlier in the season and later in the season under cooler temperatures. 


  Downy mildew has been reported in various regions of northern Ohio, warranting a ramp-up in preventative fungicide applications. Read this recent VegNet article from Sally Miller for further information and chemical recommendations. You can also track the spread on the Cucurbit Downy Mildew Forecasting website. 

Cucurbit downy mildew. Symptoms used for identification include necrotic lesions on the upper leaf surface (A) and dark, “velvety” spores on the underside of the leaf (B). Photo source: Hausbeck Lab, Michigan State University. 

  Powdery mildew is also showing up. Despite their similar names, powdery mildew and downy mildew are not even in the same taxonomic kingdom (downy is a water mold or “oomycete”, while powdery is a true fungus). Consequently, there are no fungicides that pull double-duty in controlling both pathogens. For information on products with efficacy in controlling powdery mildew, check out another recent article on the topic in VegNet

Squash bugs are out and actively laying eggs. Their copper colored egg masses can frequently be found on the underside of leaves within the veins and on leaf stalks. These pests can vector the viral disease Yellow Vine Decline, as well as cause cosmetic damage to the fruit. Threshold is met if you are finding 1 egg mass per plant. The adults are difficult to control via chemical application, so it is important to frequently scout in order to time insecticide applications to when the egg masses have hatched and nymphs are active on the plant. Spray penetration into the canopy may also limit application efficacy. 

Fruiting Vegetables

Tomato Hornworms have been observed in field tomatoes. Their massive defoliation and fruit feeding, as well as frass piles can key you into the area of active hornworm feeding. Hand removal can typically resolve minor infestations. If worms are found with white cocoons on their backs, leave them be. These are beneficial, parasitic wasp cocoons. These wasps will continue to combat hornworms throughout the season. 

Tobacco hornworm, a close relative of the tomato hornworm and fellow voracious pest of tomatoes, with parasitic wasp cocoons projecting from its body. Photo by Joe Boggs, OSU Extension. 

Verticillium wilt has been a frequent issue in eggplant this season. Initial foliar symptoms present as yellowing and dieback, typically starting at the leaf tip and working down the main vein towards the leaf petiole. While symptoms can provide some idea of disease presence, this disease can only be confirmed by testing the roots and crown at a diagnostic clinic. 

Leafy Greens and Herbs

  Second generation carrot weevil oviposition will be continuing in parsley (and related Apiaceae crops). Options are limited to control carrot weevil in crops like carrot and parsley. Trapping using Boivin Traps will help direct management efforts, but will be no silver bullet. The threshold used to manage carrot weevil in carrots is to make an insecticide application when weevils reach 1.5 beetles per trap. Celery and carrot have significantly more insecticidal options than parsley (only Baythroid). 

Carrot weevil adult. Photo source: University of Massachusetts Extension

Sweet Corn

Corn earworm and European corn borer catches across the state have been relatively low. Western bean cutworm numbers, on the other hand, have been quite high in northern Ohio. See the most recent C.O.R.N newsletter for trap catch data. Western bean cutworm is typically controlled by the same insecticides used for other lepidoptera sweet corn pests. Check out this Michigan State University Extension article on western bean cutworm management considerations.

  Japanese beetle pressure has been high this season on numerous crops including sweet corn. There have been reports of the beetles clipping silks prior to pollination, interfering with ear development and quality. This factsheet from Purdue Extension provides several insecticides for Japanese beetle control in corn, many of which are also labeled for sweet corn.

  Corn smut is a conspicuous, often sporadic fungal disease affecting sweet corn. A key symptom is the formation of grey galls that are the spore-bearing structures. Rupturing of the smut galls during harvest can taint the ears with black spores, making the sweet corn unmarketable. Corn smut is most prevalent in plants that have undergone physical damage that creates an infection entry point for the pathogen. Preventative control practices consist of crop rotation, destruction of galls before spore dispersal, and minimizing mechanical injury to plants.


Corn smut on sweet corn tassel. Photo by Chris Galbraith, OSU Extension. 


Tree fruits

Peach harvest has begun in eastern Ohio. Japanese beetle damage has been severe in some apple orchards this season. Codling moth should be slowing down now. Most growers will be making their second insecticide application to control this pest in the next week. Third generation oriental fruit moth will be showing up soon. San Jose Scale pressure should also be steadily decreasing and won’t warrant further intervention until next season. Apple maggot is still moving into orchards in plenty of sites (north and central)- keep those red sticky traps out. Spray if traps are catching >5 flies/trap. We haven’t had too many complaints about stinkbugs in orchards yet, but start trapping now if you are concerned. 


  Herbicide drift damage in vineyards (as well as other specialty crops) is a continued problem. Cassie Brown and Doug Doohan of OSU created a series of fact sheets in the past that address properly preparing for and responding to herbicide drift damage. Find the collection of factsheets here.

Some growers are beginning to apply netting over grape vines to minimize losses from bird damage.

Auxin (group 4) herbicide damage on grapes resulting from spray drift can present as cupped leaves and distorted new growth. Photo by Chris Galbraith, OSU Extension. 

Upcoming Events: 

August 23, 8:00 am – 4:00 pm, Agriculture Technology Field Day

August 24, 5:30 – 8:00 pm, OSU Extension Pumpkin Field Day

September 19 – 21, Farm Science Review

September 27, Wooster, OH, Midwest Mechanical Weed Control Field Day

December 5th – 7th, Grand Rapids, MI, Great Lakes Fruit, Vegetable, & Farm Market Expo 

January 4th – 5th, Ohio Organic Grain Conference

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