I'm not big on chemicals but we had a really bad infestation of Japanese beetles on my Plum & Cherry trees & Aphids on my Apple trees a few weeks ago. I bit the bullet & bought some GardenTech Sevin spray & mixed at 4 oz/gal. like it said. I also sprayed my Pear trees but noticed my Pear tree leaves area now a brownish green instead of the bright green they were a few weeks ago. All my Pear trees are roughly 3 years old. Is Sevin not good for Pears? Is there something else I can do or something else I can spray my trees with that's not as potent as Sevin?
Well, soapy water is lethal to aphids. Or, detergent. Anything to break the surface tension. The aphids get wetted all over, covering their breathing "pores" and they drown. Dead, dead, dead... in minutes. Gone!
I don't know the habits of Japanese Beatles, but they might dislike Mint Oil. Great insect repellent. It is an ingredient in some repellents that you can rub on your skin. Mosquitos, biting flies, and even Yellow Jackets, seem to leave you alone, when you wear it. Dr. Bronner's Peppermint soap, combines both soap and Peppermint oil. Might work.
Me? I just bought a pint of uncut Peppermint Oil from an e-bay guy down in Arizona. Gonna dilute it and spray it around the foundation of my house. Ant invasion. Hopefully, it will send them elsewhere.
You also might try Neem Oil. A little detergent, some Neem oil, dilute and spray.
I'll read up on Japanese Beetles. Seems to me they might be tough customers, and hard to kill. Might be a better strategy to make your greenery unappetizing. Let 'em go elsewhere lookin' for a palatable meal.
OK. I checked. Japanese Beetles dislike Mint Oil.
I agree with buzz off. There are a lot of plants that you can grow that will attract positive predators, and a lot of things that you can do to avoid pests without synthetic chemicals. I don't want to kill all the good guys and screw up the soil. I'd rather take the long run and make my garden a dangerous place for aphids and Japanese beetles. I don't have problems with either one because I plan so I don't have the problems. Diversification and permaculture.
My two cents.