Systemic Insecticide

Nina, I read what you had to say about the Bayer Tree and Shrub Product. A club member suggested it be used for trees such as Seju Elms and other trees with similiar bark, as well as trees that may get borers. Also this particular product kills Japanese Beetles, and we have had a bad infestation for the last three years. I have used the milky spore powder in my yard, etc., and that has reduced the infestation, but unfortunately, I can't get my close neighbors to use it. Last year most of the leaves on my maples and elms (which is what I have primarily) were decimated before August. This product is suppose to work for a year. Since it doesn't kill the bees, would it be alright to use? If not what would you recommend for borers and Japanese beetles? Thanks!

I'm not an entomologist, so you can ignore anything I say about insecticides. However, I know one of the most serious problems professional growers face is that insects get resistant to insecticides that are mis-used (mostly by the growers themselves, I hasten to say). So I don't think imidacloprid should be used for sissy insects like aphids and scales, which can be controlled merely by looking at them angrily. And I certainly wouldn't use them against japanese beetles: you can't possibly spray enough times to control them: more will come in, and all you'll do is speed their development of resistance to the product (if you have a tree they like, simply cover the tree with netting during the feeding period). Borers are another story. What I wonder, however, is whether imidacloprid is actually effective against them. I'd need to check the literature to make sure. Almost nothing is effective against borers.

My concern is this: To treat for borers, you'd need to keep the tree treated over the egg-laying period of the borer you're concerned about. If you are conscientious enough to figure out what this period is, that would be a period of about a month. Most bonsai growers are not conscientious, however, and they will nuke that tree with the systemic for the whole summer. All the other pests of that tree will be exposed to the systemic, and those pests will have the opportunity to develop resistance to it, whether or not that tree is actually being protected from the borers. So the only good way to use the systemic is to also spray a protectant on the tree as well, to make sure the other pests are killed one way or another and don't become resistant to the systemic. That's how professional growers do it, and it's no big deal for them. For the hobbyist, it takes some discipline. However, don't be wracked by guilt: if the pesticide companies wanted to keep the product safe, they would restrict its sale to registered applicators. They haven't.

I hate borers. They tend to attack stressed trees, so the best defense is a well-fertilized, well-watered tree. If you know your tree is in a high-borer area (that is, if you or someone else locally has had a tree killed by borers), you could cover the tree with a REALLY fine mesh for the danger period. You can buy insect-proof meshes in a professional nursery catalog.

OK: I just surfed the web, and it looks like, if applied properly, imidicloprid is effective against borers. For a full-grown tree, that would mean getting a certified applicator to do a high-pressure soil injection or a trunk injection. For a bonsai, however, I think anyone could properly apply the product (read the label!). If I were using it, I would only use it on a tree that was in actual peril, and I would only use it in conjuction with a protectant. But that's me.

Thanks Nina, and others. After reading the information here, and researching more about borers, I've decided to not use a systemic insecticide as a prophylactic measure. I'll just continues to use the pyola oil regularly.