What can you tell me about controlling Japanese beetles in fruit trees?
Answer: Kaolin clay is probably your best bet for organic control of Japanese beetles on apples, plums, and pears. It’s not quite so good for peaches because the peach fuzz retains the clay and thereby presents a marketing problem. Other pros and cons of Surround kaolin clay are addressed in the ATTRA publication Apples: Organic Production. Some other possible approaches to controlling Japanese beetles are outlined below.Japanese beetles can be major pests of ripening and ripe fruit. This is a serious obstacle because there are few pesticides (organic or otherwise) that are both effective against these beetles and usable up to the day of harvest. Some botanicals? such as rotenone? can legally be used even the day of harvest according to current label restrictions; however, none have proved adequate for June and Japanese beetle control.Consequently, organic growers have to resort to other methods to control these pests. Hand picking, trapping, exclusion with row covers, and reducing the immatures (grubs) in the soil with tillage, milky spore disease, and/or beneficial nematodes have all been attempted by growers with varying degrees of success. Targeting the grubs requires advance planning?the beneficial nematodes and milky spore disease are not effective against adult beetles. Grubs can be especially plentiful in undisturbed pasture or turf soils. Tillage and soil treatment with beneficial nematodes or milky spore disease are helpful in destroying pupae or grubs, but since the adults can fly in from relatively distant sites, it is often impractical to till or treat enough ground adjacent to the fruit planting to effectively suppress a local population.Commercial traps that use these pheromones for trapping the beetles are available through mail-order garden supply companies, but growers and researchers alike caution that they can end up attracting more beetles to the planting than the traps can handle, making the problem even worse. So, if you use the traps, be sure to use enough of them and clean them out regularly to make room for more beetles.Perhaps your best bet would be to both spray your fruit trees with the Surround kaolin clay as well as put out traps away from your orchard. The Surround will “push” them from your trees as the traps “pull” them elsewhere.