I wonder if I could spray malathion on the dawn redwood without harming it? The Japanese beetles like the tender leaves. I've been using liquid sevin, is that enough?
Better to use a biological control. Sevin is very toxic to all sorts of other things, including people, pets, birds, etc (it is banned in many countries).
In the United States there are systemic insecticides you can apply through a soil drench. If there is anything registered for use in your area for beetles this would be less stress on the needles. I don't know of any biological controls for beetles. I would be interested to hear if there are any. I have only ever dealt with the Viburnum Beetle where I live. I have the best control on them during the dormant spray. Because timing is very precise with contact insecticides during larvae and adult stages. As for your questions, you could spray Malathion without hurting the needles if your careful, and if your not burning them with the Sevin your using, you should be fine. And I would think Sevin should do the trick. Although it all boils down to, the larger the insect your killing, the stronger the mix you will need .vs. the stronger the mix, the better chance of burning the needles. Well best of luck, and from what I have read, I am sure glad we don't seem to have a problem with those beetles here. Jim.
thanks Jim, I was applying Sevin daily during the busy time of day for the beetles - betweeen 2 and 4 p.m. as soon as there were plenty on the tree. This seemed to take care of the problem each day without hurting the needles. I took down my beetle traps and found out I was drawing thousands into my yard from the 80 acre soy bean field directly behind the house. I thought this might be the case since niether neighbor on either side of me was having any problems. I bagged between 14 and 18 pounds of beetles with the traps in a week.
study conducted in 2005 on synthetic pesticides and organic methods of killing or repelling japanese beetles. it begins on page 21 and ends on page 23 with the results. unfortunately, not much success with the organic sprays. i did read that planting peonies will attract Tiphia, a beneficial parasitizing wasp that will get the japanese beetle grubs. you would need to plant a lot of peonies to take care of the plague of beetles some encounter. tough pest to rid of. http://www.ca.uky.edu/agc/pubs/pr/pr520/pr520.pdf
