Vermont Garden Journal: Controlling Japanese Beetles
They’re a little late this year, probably because of our cool, wet June, but they’re here. Japanese beetle adults have arrived after over-wintering as grubs in the soil and they’re feasting on grapes, cherries, plums, raspberries, basil, roses and lots of other plants. This imported Japanese native arrived in 1916 and has wreaking havoc East of the Mississippi ever since.
There are many organic controls for Japanes beetles such as spraying beneficial nematodes to kill the grubs in the soil in June and early September. Neem oil sprays can deter their feeding. Hand picking adults and pheromone traps will also work to a certain degree. But this year I’m trying two new organic sprays.
Kaolin clay consists of fine clay particles that can be sprayed on the leaves of plants. It creates a white film on the leaves that Japanese beetles hate, so they’re less likely to feed. It also is used to thwart mites, thrips flea beetles and some diseases. It washes off in rains so will have to be reapplied. I’m trying it on my grapes and cherries this year to see if the Japanese beetles will go elsewhere for a meal.
Where they probably will end up, is on my roses. Like anyone, I grow roses for their beauty, so applying a spray that will discolor the flowers and leaves isn’t very appealing. That’s why I was excited to find a new form of Bt, Bacillus thurigiensis galleriae, called BeetleJUS. It was developed to kill Japanese beetle grubs AND adults. It works like other forms of Bt. The beetle eats the bacteria on the leaves and dies soon after. It’s safe for beneficials, pets, wildlife and kids. So, hopefully, BeetleJUS to the rescue for my roses, but I’ll let you know how it turns out.
And now for this week's tip, remove spent lettuce, peas and greens from the garden and start planting kale, peas and broccoli transplants for fall. Succession planting will guarantee a bountiful fall harvest.
Next week on the Vermont Garden Journal, I'll be talking about fava beans. Until then, I'll be seeing you in the garden.