Wet weather isn’t always blessing for plants, lawns
Q: Almost all of my backyard grapes turned black and shriveled up before they ripened this year. What might have caused this, and what can I do about it?
A: The cause is black rot, one of the most damaging diseases for grapes in Ohio. The disease is caused by a fungus (
that infects the leaves, shoots, berries and tendrils of the plants.
While gardeners might miss the small lesions on leaves caused by this disease early in the season, the black mummified grapes are hard to miss.
The disease spreads rapidly in warm, wet weather, which explains why we are seeing more black rot in central Ohio this year.
Be sure to remove all affected fruit and plant parts, and dispose of them in your household trash. At the end of the season, remove all fallen grape leaves and fallen fruit and dispose of them as well.
Next spring, consider using a fungicide early in the season, before bloom through three to four weeks after bloom.
Q: I have dozens of peonies throughout my yard, and almost all of them have developed large black and brown spots on the leaves. Is this a disease that can be controlled?
A: Peony measles, also known as peony leaf blotch, is likely the culprit. This is a fungal disease that seems to be more pronounced in wet seasons and also in more-mature plants. That’s because their large amount of foliage tends to stay wet after repeated rains.
The damage is purely cosmetic and rarely hurts the plant’s health.
The fungus overwinters on dead stems and foliage, so we recommend removing peony foliage in the fall or early in the spring. Thinning out large plantings of peonies next spring also can help reduce the incidence of the disease.
Q: I recently noticed some small dead spots in my lawn that were not dead earlier in the season. I’ve seen a lot of Japanese beetles in my yard; could grubs be causing the dead spots?
A: Most grub damage to lawns in Ohio is from white grub-producing beetles, such as the Northern and Southern masked chafers.
They both have been seen in high numbers in central Ohio this season, similar to your Japanese beetles. Our wetter-than-normal summer provided the necessary soil moisture for a greater egg hatch, which means more white grubs.
To be sure that grubs are the cause of your dead spots, grab the brown turf in these areas and tug on it. If the turf peels back easily, in sheets, almost like rolling up a carpet, then grubs were likely the cause. At this point in the season, you may also find some grubs in the soil under the dead spots.
If you find that grubs are present, a rescue treatment of an insecticide such as Merit should be made as soon as possible. Follow the label directions and be sure to irrigate the treated area immediately after the application.