Q: My trees have been devastated by the Japanese beetles. They lost the top third or half of all the leaves. Will the tree be OK?

A: A healthy tree can lose at least a third of its leaves without too much ill effect. It would be best if those leaves came from the inner, more shaded areas of the plant, but the Japanese beetles start at the top of the tree and work their way down.

The plant's natural reaction will be to drop the remains of the chewed-up leaves. Then the buds at each leaf location start to grow a new stem — these would have been the stems of next year's new growth. The plant will consume carbohydrates in the process of putting out this new growth, instead of storing them for use this fall and winter when no leaves are present on the plant. They are used as an antifreeze to keep cells from being destroyed by ice crystals.

If the leaves come out soon, the plant should be fine. If the beetles or other insects eat those leaves, it would a bigger problem. If August is normal and dry, keep watering the tree. Don't fertilize it after the end of July; fertilizer can encourage growth too far into the fall, which can be damaged by frost. Wait and complete the fertilizing next spring, and hope we have a good winter for the plant's sake. Next spring pay more attention to any trees or plants affected by the beetles this year. Start any necessary treatments before the tree loses too many leaves.

Q: My lawn care provider wants to treat my yard for grubs; he says I have a lot of Japanese beetles (he is right about that). I don't want to spend money and treat my lawn on the hope that I will get the problem; however, is it better to prevent the problem in the first place?

A: Japanese beetles are not only a problem when they are adults, but also when they are in their larval stage. They are just one of several insects classified as a white grub.

Don't panic and rush out to poison your lawn. Having Japanese beetles, June bugs or other adult insects does not mean you should go out and poison your lawn to get rid of grubs. It does indicate that in August and September you should watch for grub damage in your lawn. Female beetles prefer to put eggs in watered lawns that are located in full sun, not shade. Not watering the lawn in the heat of August is OK for the lawn; it helps reduce the number of grubs. Watering a beetle-injured tree might water some lawn areas, but it is worth the risk to aid the tree.

If you find grubs, then you need to determine the amount. All lawns and flower beds will have some grubs. They aren't a big deal most of the time — it won't be worth the expense to treat only a small amount in the yard. Lawns that have few grubs can be watered; the lawn will most likely outgrow the grub problem, eliminating the need for chemical treatments.

If there are more than five to 10 grubs in a square foot, then you can economically treat. I know many people that want to use chemicals if they only find five in their whole yard, but it is just not necessary at that low level.

Chemically treating a lawn (or tree) for any insect that either doesn't exist or is only found at tolerable levels is just one more batch of chemical pollution on your lawn. It is irresponsible to pollute your property and can cause wider problems in the long run.

The most common active ingredient for grub control is imidacloprid. It is used in many insecticides for several other insects, but remains toxic to beneficial ones like bees. It is more toxic to insects than mammals, and somewhat toxic to some birds, fish and other types of animals. Imidacloprid persists in the soil long enough that it may contaminate ground water and ponds, especially if used too often. By using insecticides frequently when it is not even necessary, insects may become resistant, leaving our landscapes in bigger trouble.

Chemical poisons should not be applied to a home landscape on a regular schedule. They must only be used after determining that an insect problem is developing to a level that will require chemicals. Then use the safest treatment at the lowest dosage to reduce below a tolerable level — avoid overdosing in an effort to eliminate the problem.

E-mail questions to Jeff Rugg, Kendall County unit educator, University of Illinois Extension at jrugg@uiuc.edu. To find out more about Jeff Rugg and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.

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