Wayne County IPM Notes
(From the Week of July 19 – July 25)
Frank Becker, OSU Extension Wayne County
Hot and dry conditions are often ideal for spider mites to thrive, and this year is no different. Spider mites proliferate during these conditions and are currently doing so in melon plantings. They feed on the undersides of the leaves and their feeding damage over time can cause chlorosis and stippling, and eventually the leaf will shrivel and die. More on spider mite management
Cucumber Beetles are feeding again, primarily on young, recently transplanted squash. However, the adults are not the only ones causing damage. The larvae of the cucumber beetles have also been doing damage. I have seen damage to the skin of melons where the melon is sitting on the soil. This contact area between the ground and the melon provides the perfect place for cucumber beetle larva to feed.
I have started to see a decent amount of damage from tomato hornworms. Be sure to keep an eye on your tomato plants for large areas of defoliation near the top of the plant, as well as damage to the fruit. Tomato hornworms may also feed on Solanaceous plants such as peppers, eggplant and potato, although not to the extent of which they feed on tomato plants.
Japanese beetles are out in large numbers on a wide range of crops. Sweet corn growers should be especially wary of Japanese Beetles feeding since one of their target areas on sweet corn is the silk. The beetles can clip the silk which limits the silk’s receptivity to pollen.
Downy Mildew has now been detected and confirmed in Wayne County. Cucumber growers should have started a spray program for cucurbit downy mildew.
Powdery mildew is starting to show up on cucurbit crops around the area. If older plantings of summer squash are heavily infested and you are no longer harvesting from those areas, it would be of your best interest to terminate that crop so that you are not allowing the powdery mildew to have a place to thrive. This is especially important if you have younger, successive plantings of summer squash nearby.
This week, the lab at OARDC confirmed bacterial leaf spot on pepper. Bacterial infections have been limited this year due to the heat and dry weather, however, they should still be managed appropriately. This is one of the most destructive diseases for peppers and will result in a yield reduction due to loss of foliage and infection on the fruit.
Bacterial wilt is starting to show up in older squash plants, unfortunately at this point there is nothing that can be done. The cucumber beetles feeding on the plant while it was young vectored the bacteria responsible for bacterial wilt and the plant is finally being impacted by the infection.
Grape berry moth larvae are starting to feed and cause damage in grape clusters. Scouting grapes and carefully assessing the grape clusters can help you determine management needs. Infestations of grape berry moths are typically higher along the borders, and near woods or hedge lines as compared to the interior of the vineyard.
Spotted Wing Drosophila numbers are remaining high. Other than spraying insecticides such as malathion, it is beneficial to limit the
amount of overripe/cull fruit that is on the ground around the plants. The fruit on the ground only attracts more flies and in encouraging good sanitation in the patch it can help reduce the number of flies being drawn in.
Codling Moth traps have started to show increasing numbers, with some inconsistency, but nonetheless, the counts have trended up. Oriental fruit moth traps spiked this week, going from essentially 0 per trap to averaging between 7 and 8 per trap.
Japanese beetles are feeding across the spectrum of fruit crops that I am scouting. I have noticed heavy damage primarily occurring on ripe blueberries and on grape leaves. Left uncontrolled, the Japanese beetles can cause significant damage to blueberries and severe defoliation in grapes.
Apple and peach growers should continue their spray programs to manage fruit rots and diseases such as flyspeck and sooty blotch in apples and brown rot in peaches. Alternaria leaf blotch can be found on some apple trees right now. This can be made worse by red mite infestations. With high populations of mites and the leaf blotch, severe defoliation can occur.
Grapes should be starting to get some color to them as the clusters are starting to increase in size. At this point, most varieties of grapes should be resistant to black rot. Although symptoms of black rot may be showing up on untreated grapes, it is too late to do anything. Growers with varieties of grapes that are not resistant to downy mildew should consider a spray program. Grape growers should also keep an eye out for powdery mildew, as this is the time of year when powdery mildew is typically found on grapes.