I have a Crabapple tree and a Weeping Cherry tree. I want to know what to put on them or feed them to deter the Japanese beetles. I've heard there is something you can feed the trees through the roots and it will stop the Japanese beetles from attacking them.
Japanese Beetles on My Trees
Certified GKH Gardening Expert
There are a few things you can do. One of which is to treat your lawn for grubs. The grubs often found in the lawn are the grubs of Japanese beetles and this will help reduce their population before it starts. This article will help: https://www.gardeningknowhow.com/plant-problems/pests/lawn-grubs-how-to-get-rid-of-grub-worms.htm
The mixture you asked about will help some as well. This article has some other suggestions: https://www.gardeningknowhow.com/plant-problems/pests/japanese-beetles.htm
You may also want to plant things that Japanese Beetles do not like. This article will help with that: