Wayne County IPM Notes
(From the Week of July 26 – August 1)
Frank Becker, OSU Extension Wayne County
Flea beetles continue to be a problem in both young, recently transplanted crucifer crops, as well as cabbage and kale either in harvest or near harvest. Feeding damage from flea beetles on the younger crops can cause stunting and reduced yield. This damage can be especially impactful on heat stressed transplants. The foliar feeding being done on maturing crops can affect the visual appearance of the crop and may result in a less desirable product.
In sweetcorn, the European corn borer trap counts have shown some moth activity. A trap in Wayne County had a catch of 22 ECB moths this week. Corn earworm traps have shown little moth activity over the last few weeks. Regarding damage being done to the plants, I have started to notice increasing damage being done by armyworms. The damage I am finding is typically being done in the whorls on the young tender leaves. Another sign of armyworm feeding is large areas along the leaf edges that have a ragged appearance.
Squash bug eggs are starting to hatch, and I am starting to find various stages of larva out in pumpkin fields and squash plantings. Currently most feeding is being done on the leaves; however, the focus of the feeding can shift to the fruit and cause scarring to the skin resulting in decreased marketability. The squash bug has also been found to be the vector of a bacterium that causes the disease Yellow Vine Decline.
Downy Mildew is in Wayne and Medina counties and likely in surrounding counties as well. Cucumber growers need to be spraying for downy mildew.
Powdery mildew can be just as destructive on squash as downy mildew is on cucumbers. I have been finding powdery mildew consistently in younger squash plantings. Unfortunately, the earlier the plant is infected with powdery mildew, the shorter the life span of the plant. With an infected plant having a short life span, the yield for the plant can also be expected to decrease.
Although not a disease by definition, “fruit drop” is something that I am seeing in a lot of crops. Non-irrigated open field crops seem to be the most affected right now. Specifically looking at pumpkins, the first fruit set seems okay. The newer fruit sets are what is being impacted the most. The young fruit are being aborted by the plant, as well as the blossoms that have come on after the most recent fruit set. High temperatures and drought conditions have brought about the poor fruit set on pumpkin plants. With high temperatures affecting the viability of the pollen and the flower combined with low nutrient uptake due to limited soil moisture, the plant simply can’t sustain a heavy fruit set, at least not until we get some more consistent rain.
Japanese beetles are still feeding in nearly every crop that I am scouting. They are doing damage to apple leaves, peach leaves, grape leaves, blueberry leaves and blueberry fruit. It is important to watch the populations of Japanese beetles because they can transition from only feeding on the leaves to doing significant damage to the fruit.
After a few weeks of high numbers in both oriental fruit moth and codling moth traps, the trap counts have started to back down a bit.
On apple trees, I am starting to find some woolly apple aphids. Mature trees do not often face major damage from these infestations; however, young trees typically suffer from the damage that the woolly apple aphids cause to the roots. Continued feeding can damage or kill roots, resulting in reduced yield, growth, and tree vigor, and even death of some trees.
Overall, disease pressure has been fairly limited this year. Hot and dry conditions have prevented favorable conditions needed for disease development. As fruit continues to ripen and be harvested, we continue to move forward through the growing season without many disease issues in our area.
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.
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.