Have you noticed a lot of holes in the leaves of your trees and shrubs? Yet you don’t really see the culprits that are doing it? Here is some information from our friends at Bravo Tree Care about Japanese Beetle, the most likely suspect of leaf damage like this.
Basic summary on Japanese beetle Japanese beetle feed on over 300 trees and plants, with linden trees being one of their favorite food sources. Japanese Beetles start as grubs in the ground in the spring. Once they emerge as adults they destroy everything in their path. A tree that experiences heavy damage on a regular basis may eventually succumb to the beetle because: 1) They won’t have leaves to harvest energy from the sun 2) A weakened tree is now a target for other insects and diseases, thus a snowball effect. Usually this process happens over a few years Star Tribune article on Japanese beetle:http://www.startribune.com/lifestyle/homegarden/162731106.html
Treatments There are 3 ways to treat the Japanese beetle. 1) In the early spring, while grubs are still in the ground, an insecticide is applied to the lawn killing the grubs. This time has now passed. A lawn care provider usually provides this service.2) Usually in the spring, an insecticide is applied to the base of the tree and the tree absorbs the chemical through the roots. This treatment protects the tree for about 18 months. It takes about 2-3 weeks for the tree to move the chemical throughout its system. That is why this treatment is usually applied before the adults emerge in the spring and not while they are actively feeding. We still strongly recommend doing this application now because this treatment lasts 18 months and will last throughout all of next year.3) If the spring time tree injection is missed, a foliar insecticide spray is also applied on a weekly basis to kill adults feeding on the leaves. As of 7/23, BRAVO is anticipating 2-3 more foliar sprays.4) A tree that has experienced severe damage should be fertilized with a Potassium-based fertilizer in September. This fertilizer improves the vigor of the tree and helps improve its natural defenses.
What to Expect from treatments 1) The damage done this year can’t be reversed for this year. However, further damage will be stopped and the beetles will be killed to stop the infestation to your other plants and trees.2) Next spring, most trees should be in great shape due to the fertilizer treatments and the soil injection treatment it receives this year. Next year you won’t need any treatments as the soil injection will stop any infestation.3) Japanese beetle populations are cyclical. Usually we see infestations swell up every 10 years or so. The last 3 years have been especially brutal. This means that the infestation should be over in a year or 2 and that you won’t need ongoing treatments. In most cases, its financially beneficial to treat the tree rather than replacing it. Usually treatments will be cheaper than removal and replacement costs, and maybe the trees are old enough where you have invested at a lot of time and energy. Again, this is a real basic run through with Japanese beetle so feel free to call me or to set up an appointment. I can then explain in more detail the procedure. The bottom line is…there are solutions!