Japanese Beetles eating Blackberries
Q: We planted primo-cane blackberries two years ago in a row next to our ‘Heritage’ red raspberries. Reportedly you can cut both of these types clear down to the ground in the winter to maintain low, clean plants that aren’t brambling all over. Even though the plants are very healthy, the Japanese beetles eat all of the flowers so we got no berries. Is there a spray or something that we can use to control the beetles?
A: I’m so sorry about the berry crop. Unfortunately, any pesticide sprayed on the berry’s flowers would harm pollinating insects. Besides, we don’t know of an effective spray for the Japanese beetle. You could manually remove the beetles early every morning to lessen the damage. Even if you do get fruit to set, the beetles will eat the berries too! It appears that we will have to learn to live with the Japanese beetle. One solution, although not easy, is to build frames over the berry patch and cover it with mesh too small for the clumsy beetles to get through. Make the frame spacious enough so that you can work and maneuver while weeding and harvesting.
Because these berry varieties flower and fruit in late summer and fall, you may be able to just drape the mesh over the canes. The Japanese beetles usually disappear by mid-August then you could remove the cloth. It occurs to me that the mesh will also keep out the pollinator insects so I would recommend that you remove it as soon as you notice that the beetles have gone. If the flowers don’t get pollinated guess what! No fruit.