Editors- Thomas Becker, Agriculture and Natural Resources Educator, Lorain County and Frank Becker, Agriculture and Natural Resources Educator, Wayne County. Contributions made from team members around the state of Ohio. 

Fruit Crops

As we are on the tail end of blueberry season and entering blackberry season (at least in northern Ohio) we’ve continued to see activity from spotted wing drosophila (Drosophila suzukii) in our traps. Without traps, this is a pest we may not notice in our crop until our pickers or consumers notice soft berries or potentially even berries with live worms. Unless our customers are okay with a little extra protein in their fruit, this could be enough to keep folks from coming back to a farm for their berries. If you are a long-time reader of the Specialty Crop Newsletter, you may recall that one thing that sets these fruit flies apart from others is the fact that the females possess a serrated ovipositor that allows her to lay eggs in ripe fruit on the plant. Our more traditional fruit flies or vinegar flies must wait for fruit to be overripe or rotten before they infest it. Thus, the importance of a good integrated pest management program that utilizes trapping so growers can make timely decisions to manage this economically important pest. Trapping can be critical because the action threshold for spotted wing drosophila (SWD) is 1 fly. What can be tricky for growers is distinguishing between SWD and other fruit flies in the trap. In the Extension office, we have to make use of a microscope to ensure we are getting a proper ID. That is where growers might be able to work with their Extension educator to see if they can assist with trapping or go to the OSU South Centers web page to look at the specialty crops trapping data that is updated in-season. You can find that at this link: https://southcenters.osu.edu/horticulture/eplus/specialty-crops-insect-trapping. Another thing we can do in the field to see if our berries are infested is a saltwater test. Place a sampling of your fruit in a shallow container with some salt water. Smash the fruit a bit to allow the saltwater into the fruit and allow it to set for a few minutes. If the berries are infested with SWD larvae, the larvae will float to the top. If you are looking for a list of effective insecticides, Penn State University provides a list of products with efficacy ratings of good or excellent along with the IRAC codes and pre-harvest intervals for each product. Remember that a good pest management program rotates pesticides based on their group numbers to help prevent resistance building up in pest populations. Paying attention to pre-harvest intervals can be especially important for growers that have U-pick fields. This information can be found here: https://extension.psu.edu/spotted-wing-drosophila-part-4-management.  

Vegetable Crops

Numerous disease challenges have continued to be troublesome for growers all over the state.  

Cucurbit downy mildew has now been confirmed in Medina and Wayne counties. As shared by Vegetable Pathologist, Dr. Andres Sanabria-Velazquez , “Recent climatic conditions, including frequent overnight leaf wetness from dew, daytime temperatures in the mid-70s Fahrenheit, and intermittent rainfall, have created an ideal environment for pathogen development. Although current incidence and severity remain relatively low, the pathogen’s rapid disease progression under these conditions poses a significant threat to yield if left unmanaged. 

Immediate management should be with a protectant fungicide spray program targeting oomycete pathogens and subsequent applications planned at weekly intervals. Canopy thinning can be performed to improve air circulation and reduce leaf wetness. Fields will need to be scouted every three to five days to assess treatment efficacy and adjust application timing. Severely affected foliage can be removed and destroyed to limit inoculum, and equipment sanitation protocols should be reinforced to prevent spread to adjacent fields. 

Recommended active ingredients include chlorothalonil, mancozeb, cyazofamid (Ranman), the ametoctradin + dimethomorph combination (Zampro), and oxathiapiprolin (Orondis Opti). To reduce the likelihood of resistance, these fungicides should be rotated based on their modes of action. Moreover, preventive applications made before pathogen establishment are essential for the most effective disease control. 

Field diagnosis alone can be misleading. Many foliar symptoms overlap, and mixed infections are common. Accurate identification requires observation of the pathogen’s microscopic structures (conidia, sporangia, bacterial streaming, or hyphal morphology) under a compound microscope. Please consider submitting fresh or well-preserved samples to the Plant and Pest Diagnostic Clinic 

Additionally, a grower submitted photo was shared with a county extension educator and while a sample has not yet been processed to confirm, the photo showed clear signs and symptoms typically associated with southern blight of tomatoes. This is a disease that thrives under hot, moist conditions – it is not common in northern Ohio, but we have seen it before in central and southern Ohio. An elongated brown lesion on the lower stem and root rot was accompanied by white mycelium, sometimes clearly in a fan shape, at the base of the stem. Small, round sclerotia eventually form on the surface and serve as overwintering structures. Sclerotia can survive many years in the soil, so it is important to remove diseased plants and accompanying sclerotia from the field. 

Crucifers have also had their fair share of disease challenges. Lab confirmed samples of bacterial head rot and Alternaria leaf blight has growers concerned about next steps to protect their cabbage, broccoli and cauliflower. Alternaria causes round or oval bullseye lesions on leaves and stems of cole crops. Yellowing of tissues surrounding the lesions, as well as leaf drops, may also occur. While Alternaria lesions generally do not progress deeply into the head, they are unsightly and may render the heads unmarketable. Secondary soft rot infections can cause significantly more damage to the heads than the initial Alternaria infection. As for the bacterial head rot, symptoms start as water-soaked areas on small groups of unopened flowers on immature heads. These infected florets become necrotic and turn brown to black in color. The symptoms start to spread to surrounding florets and other areas of the head, eventually affecting larger areas of the head. Soft rot then develops in the infected tissues, meaning that the tissues turn soft and slimy. A bad odor is often associated with this rotting. After the initial infection, secondary bacterial and fungal pathogens can invade, causing further rotting of the tissue. 

Insect pests are also increasing in activity. There has been observed and reported pressure or damage from potato leafhoppers, corn earworm, European corn borer, aphids, spider mites, imported cabbage worm, flea beetles and Colorado potato beetles, among others. We have had ample southern winds and accompanying warm temperatures to allow for migratory pests to arrive in abundance and for all our insect pests to complete their generations and life cycles rather quickly. Frequent scouting or use of insect pest monitoring traps are the best ways to ensure that your crops are not facing economic levels of damage and that any management decisions or applications can be made at the most effective time.