The later weeks of July are usually when the activity of damaging insects seems to reach its peak. This is when some of the most damaging insects have the potential to destroy certain types of shrubs, trees and food crops.
These are the ones you need to be on the watch for.
Japanese beetles are metallic green and bronze beetles that peak in July. They feed in groups, skeletonizing the leaves of the plants they are feeding on. Roses are a favorite target. Other vulnerable flowers include hibiscus, hollyhocks and cannas. Trees they are most attracted to are Japanese maples, lindens, crabapples, birch and pin oak. Food crops are also targets such as grapes, raspberries, and stone fruits like peaches, plums and cherries. Vegetables include green beans (pole beans), soybeans, corn silks, asparagus and basil.
They can be controlled with either chemical or organic treatments. Chemical treatments give the best and fastest results. These would include insecticides containing pyrethroids or carbaryl can achieve broad control. These insecticides provide quick control to protect high-value fruit and vegetable crops from being decimated during the peak summer flight period.
Neem oil can be used as an organic option for these beetles. Neem oil works as a repellent to repel adults and suppress feeding. These treatments break down rapidly in sunlight requiring multiple applications.
Two-spotted spider mites are tiny, sap-sucking arachnids that thrive in hot, dry weather. They are microscopic and cannot be seen. They target over 300 plant species. Key targets include landscape shrubs like burning bush, vegetables like tomatoes, cucumbers and beans. Perennials and annuals can also be vulnerable. To identify, look for fine webbing on the undersides of leaves and yellow speckling.
Neem oil is also the best product to treat spider mites. Insecticidal soaps can also be used. To effectively treat them you need to spray both sides of the leaves as they can live on the underside. This is done most effectively with a pressurized tank sprayer.
Late July is a critical window for squash and pumpkins. If you are growing these, you need to watch for Squash Bugs & Squash Vine Borers. Scout the undersides of leaves for clusters of bronze squash bug eggs and check stems for wilting caused by borer larvae.
Finding the eggs gives you the best chance of keeping these insects from causing major damage. When the eggs are present you can treat the underside of the leaves with insecticidal soaps or an insecticide containing pyrethrins. This will prevent them from reaching adult stage. Once they reach this stage, it is very difficult to prevent the damage.
Keep an eye on your tomatoes for Tomato Hornworms. These massive, bright-green caterpillars can rapidly defoliate tomato plants. Look for their dark droppings (frass) on lower leaves. They can be big in size but hard to see as they camouflage themselves well with the leaves. The best thing to do is pick them off and destroy them. You can also treat with Spinosad.
I cannot finish this article without also reminding you about the box tree moth whose caterpillars can destroy your boxwood plants. These have mostly been a problem in Eastern Hamilton County, but they have been moving into surrounding areas.
The box tree moth lay eggs in the center of the boxwood plants. When the eggs hatch and become caterpillars, they eat the plant from the inside out. Most of the time the plant is gone before you discover you have a problem. Spinosad is the best insecticide for treating these insects. You cannot spray to prevent. You need to watch for them and spray when you have the caterpillars.
If you discover you have any of these insects and choose to spray for them, do this in the early morning or the evening. Spraying during the day with summer heat can cause more damage to your plants from burning.
This article originally appeared on Cincinnati Enquirer: These insects are coming for your shrubs, trees and food crops this July
Reporting by Chris McKeown, Special to The Enquirer / Cincinnati Enquirer
USA TODAY Network via Reuters Connect
By Chris McKeown, Special to The Enquirer | USA TODAY Network
