I just noticed my first JB last night. Given the fact I've just purchased some young JM's, would it be prudent/wise to active proactively by administering a systemic to the roots or should I take a wait and see approach? Do young trees like these tolerate systemics well? bkfisher
Since you mentioned that you just noticed your first Japanese beetle, did you just move to this neighborhood,? Have you ever lived in an area with Japanese beetles before? Have you asked anyone in your neighborhood how bad the problem is? Or have you just purchased these young trees and knew to watch for Japanese beetles? Apparently Acer palmatum is one of these critters’ favorites foods. The good news is that I only found one thread on this topic here in the Maples forum, so maybe the problem can be held in check: http://www.botanicalgarden.ubc.ca/forums/showthread.php?t=3250&highlight=beetle. Also, check out these websites, one of which is from KY across the river: http://www.aphis.usda.gov/lpa/pubs/pub_phjbeetle04.pdf and http://www.uky.edu/Ag/Entomology/entfacts/trees/ef409.htm. Breezing through the articles I did not notice anything about systemics. Unfortunately, one of the recommendations is to avoid planting their favorite foods.
Laurie, Thanks for the reply. It appears this topic is a sensitive one. My intent wasn't to start a fire-storm. I rarely use insecticides and only as a last resort. If you don't live in an affected area, you can't appreciate the plague-like proportions one experiences of these beetles and the damage they can do. bkfisher
you won't just see one, you will see many more. they can completely defoliate your plants. I have dealt with them for the past several years. Since ***. Maples are not inexpensive trees, I would do some spraying. As far as I know, systemics don't work in time. By the time the chemical makes its way to the foliage, the damage is already done. You need to purchase a contact spray to kill the ones you see feeding. They will return again and again until they go back into the ground to lay their eggs for next year, which is towards the end of July and into August. We have had pretty good success with starting from the ground up. In September and March, we applied a granular insecticide called "Kill-a-Grub", fairly cheap. Milky spore will do the same thing, but takes several years for it to kick in. This will kill the ***. beetle grubs before they emerge next summer. When you apply it in September you will get the newly laid eggs and whatever eggs it doesn't kill you have a second chance to kill the grubs in March when they are coming back up to the soil surface. ***. Beetle control is most successful when it is a neighborhood battle. If you have plants they like, ***. maples, hardy hibiscus, crepemyrtles, roses, you are inviting them into your yard. I don't like to use chemicals either, but they WILL defoliate your ***. Maple. I would look at your farmer's COOP for available products. The traps they sell do trap them, but once again when you set traps you are inviting them into your yard. Not only do you trap the ones you have, but you also attract your neighbors unless they set up traps too. One of our clients had 12 traps on his 2 acre property. I would have to empty all 12 bags every other day or they would be spilling out over the top because there were so many. If you do the traps, you need to set them away from your plants you are trying to protect, like on the edge of your property. I don't know how severe they are in IN, but in NW Arkansas they are like a plague for 2 months. Good Luck!
In response to your question on proactive versus reactive approaches to the problem, Van Gelderen, in Maples of the World (Timber Press 1994), writes: “To sum up the impact of diseases and pests on maples, prevention is the best means for dealing with damage to plants, be it environmental, viral, bacterial, fungal, or by insects. Improving any favorable element in the tree’s situation – proper fertilization, watering during dry spells, periodic spraying for leaf-chewing insects and blighting fungi, and proper pruning of infested or weakened branches – is the best remedy.” Several websites mention that odor and location in direct sun seem to be very important factors in plant selection by the beetles. Since variegated cultivars actually often do better in a shady spot, would placing the cultivars in the shadiest spot be a possibility to add to your arsenal of deterrents, since the Japanese beetles will likely be a recurring problem? Fortunately, we do not yet have to deal with Japanese beetles here, and I don’t have any experience with systemics, in general. I do know that rosarians deal with Japanese beetles, but typically do not recommend using systemics. Acer palmatum leaves are more delicate, and I think that is what you are inquiring about: what chemicals to use that are safe for the leaves. It seems that the linked articles above mentioned neem oil and Pyola – pyrethrins and canola oil. You could call Gardens Alive, the manufacturer of Pyola, to inquire if the product is safe to use on variegated maples: (513) 354-1482. I used the advanced search option to check for threads in the Maples forum using first “insecticidal soap,” then “neem,” and found some articles, which may or may not be helpful. Unfortunately the links from the searches are not working. In one of the threads Layne mentions: “Stay away from oil based insecticides with regard to maples.” It might be worthwhile briefly reading through them. I would definitely be interested in knowing what works best for you and the beetles.
