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Fruit tree spray schedule and adult Japanese beetle control

By John Fulton

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[March 10, 2009]  When it comes to spray programs for apple and pear trees, the two rules are to be consistent and be persistent. Quality fruit these days takes these two things, and time.

It seems like quality fruit must be sprayed at the recommended intervals. Starting with dormant oils, these need to be applied before buds swell. Dormant oils are usually needed only every two or three years to provide control of scales and mites. Sure, the populations will build up in the off years, but should remain relatively low if the three-year program is followed. Dormant oils do require temperatures above freezing for 24 hours, but you want to be ahead of the bud swell.

The first regular spray of the year is applied when the green tissue is a half-inch out of the bud. The spray homeowners use usually consists of a multipurpose fruit spray (and sulfur if needed for powdery mildew). Multipurpose fruit spray has been reformulated the last few years to include malathion, captan and carbaryl (methoxychlor was eliminated from the old mixture). This same mixture would be used when the fruit buds are in the pink stage (when fruit buds show color). After that, the persistence and consistency pays off as you spray with the same mixture about every 10 days until we get to within two weeks of harvest. In our area, we need to continue spraying this late because of apple maggot and sooty mold.

This spray program will also control borers on apples and pears, if you also thoroughly spray the trunk and main limbs of the trees. On non-bearing, young fruit trees where borers have attacked, you can spray the trunks every two weeks during June and July with a multipurpose fruit spray.

The spray schedule for peaches, nectarines, apricots and plums varies a little bit. The dormant spray for them uses captan fungicide. This is the only spray that controls leaf curl and plum pockets. The next spray is with captan when fruit buds show color, followed by captan at bloom. When the husks begin to pull away from the base of the fruit, we would then spray with sulfur, captan and malathion. This mix would then be used every 10 days or so to within a week of harvest.

For borers on the peach group, you can spray or paint the trunk only with carbaryl (Sevin) on June 15, July 15 and Aug. 15. We have some challenges with the loss of some of the insecticides, since carbaryl can cause fruit drop or thinning on the peach group and some apples.

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Adult Japanese beetle control

Application of imidacloprid (Merit and other brand names) and other systemic insecticides is effective in controlling Japanese beetle adults. Although the imidacloprid occasionally doesnít work in a tree to control this pest, it does over 80 percent of the time. However, a soil application of imidacloprid typically takes six to eight weeks to move completely up to the leaves of large trees. With Japanese beetle emergence typically starting the fourth week of June in our area, the sooner the better for application. This would be a prime option for linden trees, crab apples, rosebushes and other favorites of the Japanese beetle.

Imidacloprid can be soil-applied either as a drench or by injection. Because imidacloprid is easily tied up on organic matter, mulch and other dead organic matter must be removed from around the base of the tree before a drench application is made. Removal of turf around the tree would also be recommended for a drench. Soil injections should be made deep enough to get below mulch, turf thatch and other organic matter, but not deeper than 3 to 4 inches. Apply to the soil within 1 to 2 feet of the trunk, where the greatest concentration of fine feeder roots is located.

Just remember, each beetle must eat some leaf to get the insecticide. If a million beetles all take two bites of your linden leaves, there are still going to be a lot of leaves eaten. Donít use this treatment on fruit or small fruit trees unless labeled accordingly.

[By JOHN FULTON, University of Illinois Extension, Logan County]


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