Month: July 2023

OSU Extension Bi-Weekly Fruit & Vegetable Report – July 7th 2023

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

Air Quality

With the recent poor air quality caused by wildfire smoke, questions were filtering into county offices regarding potential effects on crops. One of the major potential concerns is ozone damage to plant tissue if there are significant concentrations in wildfire smoke. Check out this article from University of Minnesota Extension for more information.

A question came in from the community asking if the smoke from the Canadian wildfires would affect the ability to eat lettuce from their garden. Information from Jennifer Little, Family and Consumer Sciences Extension Educator in Hancock County, cited that according to the Environmental Protection Agency (EPA) and the United States Department of Agriculture (USDA) that there should not be any issue with consuming the lettuce. Folks can follow normal harvesting/cleaning processes prior to consuming vegetables. Any harm to humans would be from breathing the smoke-filled air, which could cause respiratory issues. Therefore, the concern is not in consuming the lettuce but in spending time outdoors. It is wise to take precaution with the amount of time you are spending outside when air quality is poor, especially if you have underlying respiratory issues. More information on air quality can be found on the Ohio Department of Health’s website.

Crop updates

Vegetables

Beans/Peas

A number of insect pests are being found in bean plantings, including Japanese beetles, Mexican bean leaf beetles, and potato leafhopper. Aphids have also been found in beans, as they have been found in many other crops this year. With the extremely elevated number of aphids, there has been ample opportunity for natural enemies such as predatory and beneficial insects to also build their populations. Species such as lady beetles, predatory stink bugs, and parasitic wasps are being found in abundant numbers. Signs of natural enemy activity include “aphid mummies”, which are the remains of aphids resulting from parasitic wasps laying their eggs in the insect. When the eggs hatch, the wasp larvae consume the host from the inside, leaving behind only the dried outer shell of the aphid.

Aphid mummy present in an alfalfa field. Photo by Frank Becker, OSU Extension.

Brassicas

  Cross-striped cabbage worm is being detected in eastern Ohio. Check out this article from Kansas State for a quick primer on this insect pest. 

Cucurbits 

  Striped cucumber beetle pressure is sporadic across Ohio, with some farms showing high populations and levels of damage while others show very little. Even plantings where the Farmore FI400 (thiamethoxam) seed treatment was used are showing outsized amounts of feeding. For information on integrated cultural management practices to use, check out this article on non-chemical striped cucumber beetle control.

Squash vine borer (SVB) egg laying is underway. Check out this article from Michigan State University Extension on SVB biology and control to learn more about the pest’s life cycle. Squash vine borer is one of the many insect pests that OSU Extension’s IPM program traps throughout the growing season to monitor population spread and density. For more information on how to use trapping to monitor this pest, check out this instructional video from the OSU IPM program. 

  Mice and vole feeding on young cucurbit seedlings this year has been severe and exacerbated by the dry weather. Wildlife damage in fruits and vegetables persists as a problem for which there are no surefire solutions. Tactics for preventing wildlife damage include employing netting, fencing, repellants, trapping, and other lethal/non-lethal deterrents. Resources include the Ohio DNR Nuisance Animal Control Manual and Wildlife Management Factsheets from the USDA/Michigan State University Extension.

Root crops 

High thrips populations are currently being observed in maturing onion crops.

Both homeowners and commercial garlic growers alike have been impacted by garlic bloat nematodes this growing season. This pest will damage other plants in the allium family as well, including onions, chives, and leeks. Some of the symptoms we see resulting from damage caused by garlic bloat nematodes are stunted leaf growth, distortion, yellowing, wilting, and premature dieback of the leaves, as well as bulbs that can look rotten since the damage opens up the plant tissue to be infected by other bacteria and fungi. As shown in the pictures (below), the roots can be partially or completely missing.

Garlic bulbs showing damage caused by garlic bloat nematode. Photos by Thomas Becker, OSU Extension

The best thing that garlic growers can do to prevent future crops from being infested is to rotate out of alliums and to use fresh seed every year. Mature, reproductive nematodes can live in the bulbs both during the growing season and while in storage. Growers that use saved seed from the previous year’s crop are risking re-infestation. Crop rotation is encouraged for many vegetable crop species to help break pest and disease cycles.    

Colorado potato beetles are being sighted, primarily in organic and volunteer potatoes. Refer to the Midwest Vegetable Production Guide for chemical options for Colorado potato beetle control. 

Tuber quality in potatoes can be impacted by a number of variables over the course of a growing season. Specifically, tuber formation can be impacted by management factors like planting depth and hilling intensity- learn more in this recent article from Matt Kleinhenz of OSU Extension.

Potato flowering signals the start of tuber bulking period. Photo credit, Chris Galbraith, OSU Extension. 

Sweet corn

First plantings of sweet corn around both Huron and Seneca Counties were wiped out by Spring frosts, with later plantings expected to have low yields from both frost damage and heat/drought. Corn earworm is being caught in traps near sweet corn plantings, while European corn borer catches are low. 

Fruits

Tree fruits

  Despite the dry spring, the pome and stone fruit crop is looking good for the season. Sporadic hail storms near the end of June have caused some damage in apple orchards, as well as to other crops. 

Small fruits

Blueberry u-picks in southern Ohio have opened up to the public. Late frosts in north-central Ohio killed most strawberry blossoms in both matted-row and plasticulture systems, leading to a drastically reduced crop.

Gary Gao, OSU professor and small fruit specialist, received a few messages about the collapsing of blackberry floricanes before fruits reach full maturity. Miki and John Pringle sent him a few pictures of the dying canes. They said that the affected canes turned white and died. The problem was not widespread on their farm. The Pringles grow their blackberry bushes on a rotatable cross arm trellis (RCA). The plants had winter protection with row covers when most parts of Ohio experienced the low temperatures in December 2022. However, it was still possible that some spots of the blackberry patch were not protected well due to holes in the row cover and weaker bushes. 

Gary attributed this problem to blackberry cane blight triggered by cold injuries. Cane blight is a fungal disease. Growers who grow blackberries on RCA are encouraged to put on a dormant spray like Sulforix before they cover the blackberry plants with row covers in December. This is probably the reason that Pringles only saw this problem on some bushes. Growers who grow blackberry bushes in a traditional hedge row without winter protection are not as lucky. Cold injuries induced cane blight are showing up around late June and early July. The affected canes will completely collapse before fruits ripen. It is very disheartening to see since growers invested a lot of time and money on managing the canes. This is why the use of Rotatable Cross Arm trellis with 3 oz. row covers is recommended if growers desire consistent production year after year. 

Collapsing blackberry floricanes from cold injuries and possibly cane blight. Photo by John and Miki Pringle, Pringles Orchard, Goshen, Ohio.

A good way to assess the damage from cold temperatures is to cut the bark to see if the cambium tissue is healthy. Healthy cambium looks light green while dead cambium is dark brown. The ideal time for doing this is April. By then, growers can determine if it is worth all the time and expenses to manage the bushes. If the cambium tissue of the floricanes is damaged and the damage is widespread, growers may elect to cut out all of the damaged canes in April and call it a total loss. 

Floricanes with light green healthy cambium tissue. Photo by Gary Gao, The Ohio State University. 

Blackberry floricanes with dead cambium tissue. Note the dark brown area between outer epidermis or the bark and the xylem or the woody tissue in the middle of the cane. Photo by Gary Gao, The Ohio State University.

Blueberry and Raspberry Harvest Update: Blueberry and raspberry harvest is in full swing in early July. Most blueberry and raspberry growers do pick your own. The crops look quite good despite all of the weather challenges with cold temperatures in December 2022, warm winter, and a drought in spring. It is nice to see rain across Ohio. If you did not see much rain in your area, it is very important to irrigate the bushes to keep plants health and make the fruits grow. 

Ripe Bluetta Blueberry ready for harvest. Photo by Gary Gao, The Ohio State University.

 

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

 

Upcoming Events: 

July 12, 10:00 am – 2 pm, Ontario AgRobotics Field Tour, Part 2

July 20, 9:00 am – 1:30 pm, In-Field and Edge-of-Field Conservation Practice Field Day

July 20, 8:30 am – 3:30 pm, “Climate Smart: Farming with Weather Extremes” conference

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

August 24, 5:30 – 8:00 pm, Western Ag Research Station Pumpkin Field Day

September 19 – 21,  Farm Science Review

September 27,  Midwest Mechanical Weed Control Field Day

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

January 4th – 5th, Ohio Organic Grain Conference

 

Cucumber Downy Mildew Reported in Ontario, Canada

Cucurbit downy mildew map – click on map to enlarge it. https://cdm.ipmpipe.org/

Downy mildew was found on cucumbers in Haldimand-Norfolk, Ontario on July 1 and Chatham-Kent, Ontario on July 4. Even though it has been hot recently, cooler nighttime temperatures and cloudy skies can allow the spores of the downy mildew pathogen to survive during transport from source plants in Ontario on air currents, and to infect cucumbers and melons. The spores are usually deposited on plants during rainfall events. In our experience, we can find downy mildew in northern Ohio 1-3 weeks after outbreaks in these counties in Ontario, depending on the weather. Normally we only see Clade 2 isolates in northern Ohio during this time. Clade 2 isolates attack only cucumbers and melons e.g. cantaloupe, and circulate primarily in the Great Lakes region. Clade 1 isolates attack watermelon, pumpkins, squash and other cucurbits and work their way up the east coast from Florida and into the eastern parts of the Midwest. We see them mainly in southern and central Ohio in August or later in most years. The clades of the downy mildew pathogen differ somewhat in sensitivity to fungicides, so Ohio growers should use recommendations for fungicides from labs in this region.

Before symptoms appear in northern Ohio, cucumbers and melons should be protected with a chlorothalanil or mancozeb product. Fields should be scouted often; once downy mildew is reported in the northern Ohio counties, growers should add an effective downy mildew fungicide to their protectant (chlorothalanil or mancozeb) spray program. Good options for Ohio are Orondis Opti (FRAC 49+M05; contains chlorothalanil so don’t tank mix with additional chlorothalanil), Previcur Flex (FRAC 28), Elumin (FRAC 22), Ranman 4SC (FRAC 21), Omega (FRAC 29), and Zampro (FRAC 45+40). For more information on these fungicides, see here (OSU data until 2021) and here (Michigan State University 2022).

See my June 24, 2023 post for pictures of symptoms and instructions for submitting live or digital samples to OSU for diagnosis. Diagnosis is free for Ohio growers thanks to a grant from the Ohio Produce Growers and Marketers Association’s Ohio Vegetable and Small Fruit Research and Development Program.