Q. My mint and snapdragon plants seem to have a disease. The leaves are covered with rows of small, round spots. The plants seem OK otherwise, but I'm concerned that the problem may get worse and spread to other plants. What am I dealing with?
A. You're probably dealing with the four-lined plant bug, an early-season insect pest that feeds on a variety of herbaceous and woody plants. The spots you see are where it has chewed.
The adults are yellowish-green with four black stripes. The nymphs are bright red in color. This is a fast-moving pest that is difficult to kill with an insecticide. Affected plants typically grow out of the problem.
Q. I planted a zoysia grass lawn ago years when KY 31 was th only available fescue. My lawn has deteriorated over the years and now is full of weeds. I'd like to make the switch back to fescue. Can I do it now?
A. No, it would be better to wait until late summer to plant a cool-season grass such as fescue. In mid-August, do the following: Take soil samples, kill the existing zoysia grass with a nonselective herbicide, amend the soilaccording to soil-test results,rototill and rake out and smooth the entire area. In late August or early September, sow a recommended turf-type tall fescue cultivar and keep the area well-watered and covered lightly with straw.
Q. I love the flavor of some of the heirloom tomatoes I've bee buying at farmers' markets. This past year I planted a whole row of "Tappy's Finest," an old heirloom variety. They all wilted and died in the middle of July. They had no leaf blight or spider-mite problems. What might have happened? Is it something that came in on the seed?
A. Sounds like fusarium wilt, a soil-borne fungal disease that devastates susceptible cultivars. If you had sliced into the stems of your plants, you probably would have seen browning of the vascular system, a tell-tale sign of the disease.
This year, you should plant cultivars that have resistance to two or more races of fusarium wilt. The resistance level is designated on the plant label next to the cultivar name. Look for "F," "F1," "F2" and "F3."
Garden tips are provided by the Home and Garden Informatio Center of the Cooperative Extension Service of the University of Maryland. For more information on these questions, or if you have questions of your own, call 800-342-2507, or visit its Web site at http://www.agnr.umd.edu/users/hgic.
This week's checklist
* Prevent blossom-end rot of tomatoes, peppers and squash by incorporating a handful of lime into the planting hole soil. Also, keep plants mulched and well-watered.
* If you've had a serious problem with Japanese beetle grubs, apply a lawn insecticide with the active ingredient imidacloprid (Merit) between now and late July.
* Place collars (small paper cups or aluminum pans with the bottoms removed) around vegetable plants to prevent cutworm feeding.
Pub Date: 5/17/98