Purdue Extension Service

Vanderburgh County, Indiana

Problems Bugging Local Gardeners

By Larry Caplan, Extension Horticulture Educator, Vanderburgh County, IN

For the Evansville Courier and Press, July 18, 2008

As is usual for this time of year, numerous insect, disease, and weather-related problems are creating problems for local gardeners.

One interesting injury I'm getting a surprising number of calls on deals with the fruit of blackberries. Some of the drupelets (the tiny "bumps" on the fruit) are failing to turn red and black, but instead remain white. Sometimes the drupelets turn brown and shrivel. There is no rot, no signs of mold, and no insects. This is a condition known as "white drupelet disorder," or sunscald, and it's basically caused by high temperatures and exposure to the sun. High levels of ultra-violet radiation may be one of the major culprits.

Affected fruit look a little strange, and some folks say this affects the flavor if eaten fresh. However, the fruit are perfectly safe to use for cooking or processing.

There's no specific control for this condition. If you're seeing a lot of this on your fruit, you might try erecting a shade screen over the berry patch. Protect the plants from any insect or disease problems that damages the leaves, which may allow more sunlight through. Proper pruning and fertilizing will also help.

Squash plants are reportedly drooping and wilting suddenly. Although many things can cause a squash plant to wilt, be on the lookout for damage from the squash vine borer. Masses of greenish-brown frass will be pushed out of the entrance hole at the base of the plant. A white grub-like caterpillar causes the damage by boring into the vine. The adult is a clearwing moth that looks like a wasp and is active in the daytime.

Once the larva is inside the vine, it's too late to control it. The best control method is to spray carbaryl (Sevin) twice 7 days apart, beginning when the vines start to run. Destroying crop residue will also reduce squash vine borer problems next year.

There are many lawn diseases that can cause dead patches in your yard. Usually, these don't cause any really serious problems in the home lawn. However, one disease has recently appeared that is frustrating homeowners because the spores are turning their shoes and socks black! This is striped smut, which has not been a problem in the tri-state for many years.

Striped smut is a fungus disease that mostly hits the older varieties of Kentucky bluegrass. Cool temperatures in the spring and fall favor development of this disease. Infected plants are pale green to slightly yellow. Leaves develop black sooty or powdery stripes that run parallel with the leaf veins. The sooty substance is composed of masses of fungal spores.

The best control for smut is to grow resistant species and varieties of turfgrass. For existing lawns, a lawn company can apply certain fungicides in the spring or the fall. Proper watering, fertilizing and mowing give your lawn the best chance at recovering.

For more information on current yard and garden problems, contact the Purdue Extension Service at (812) 435-5287. During the week of July 21-26, I will be at the Vanderburgh 4H Fairgrounds, so come visit me out there!