July 15, 2008
Using Traps on Japanese Beetles Not Effective Way to Control Pest
By Chris Kick
Q: My trees are getting eaten up by Japanese beetles. What should I do?
A: Japanese beetles have definitely made themselves known this past week. But do not put out beetle traps. Research has shown that, despite the number of beetles the traps catch, they actually bring more of them into the area where they are placed. If you do want to use traps, place them away from any plants you want to protect. If the trees are not too big, hand picking them and putting them into soapy water is an option.
Otherwise, we have to turn to insecticides to control the beetles. Sevin is an inexpensive, easily found insecticide that will provide a quick kill of the beetles. It comes as a dust that can be applied over smaller plants or as a liquid or powder that can be mixed with water and applied as a spray. "Organic" insecticides such as rotenone or pyrethrum also will give good control. Whatever you use, make sure to read the label, follow the directions and make sure both Japanese beetle and the plant you want to protect are listed on the label. For trees too tall to spray, the use of Bayer Tree and Shrub Insect Control may be an option. Mixed with water according to the instructions on the label, the solution is applied as a drench around the base of the tree so the insecticide can be taken up by the roots and translocated throughout the tree. Although this will work for beetles, the active ingredient in this product does not work on caterpillar-type pests such as gypsy moths.
Q: The leaves on my green beans have started to wilt and dry. There does not seem to be any insect damage or discoloration, but I am finding something that looks like cotton on a few of the stems. Any idea what could be the problem?
A: What it sounds like is a disease called sclerotina or "white mold." To verify this as the problem, check underneath the cotton- like growth or inside the stem to see if you find any small, black fruiting bodies. They resemble rat droppings. These fruiting bodies, called sclerotia, are the over-wintering structure for the disease and will fall to the ground to carry on the disease next year when they form a tiny mushroom-like structure that releases spores to infect plants and start the process all over again. Many types of plants can get this disease, just a few of which include tomatoes, cabbages and potatoes. The only two common vegetables I know of that are not known to get it are sweet corn and onions. Rotating these nonsusceptible crops into an area known to have it is one control measure. Other than that, the best thing to do is remove those plants infested with it, put them in a garbage bag and send them to the dump. Do not try to compost these infested plants because you will only spread the disease when you put the compost on your garden. Even burning them will not destroy the sclerotia.
Questions for this column can be mailed to Round Yard and Garden at 428 W. Liberty St., Wooster 44691. It is your questions that make this column possible.
Ron Becker is an OSU Extension program coordinator.
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