Integrated Pest Management, or IPM, is a strategy used to control pest populations and minimize plant damage, as well as risks to humans, nontarget organisms and the environment. The program uses a combination of control techniques.
The first step is to determine if management is needed; monitoring and correct pest identification will help decide this.
We have been noticing adult Japanese beetles on numerous plants and adult potato beetle on the potato plants in the SMART Garden. At this point in time, we have observed about 10 percent leaf skeletonizing from the Japanese beetle and less than 1 percent damage from the potato beetle. Most plants can tolerate the loss of about one third of their leaf area.
The potato beetles are few in number, so we easily have been hand-picking them off and dropping them into soapy water to drown. Hand-picking the Japanese beetle has not been so successful due to their numbers. Hand-picking is a mechanical control technique and is working with the potato beetle, not so much with the Japanese beetle.
Another mechanical control would be a pheromone trap. Research shows these traps don't work for Japanese beetles but do work for other pests. The trap for Japanese beetles attracts more than it catches, resulting in a surplus of beetles. I have considered hanging traps in the trees across the road, luring the beetles away from the garden.
A physical control would be fencing, netting or screening to keep pests away from plants. We covered the fruit trees in the SMART Garden with bridal veil netting or tulle to prevent the Japanese beetles from feeding on the leaves. The netting also prevents other pests such as codling moth and apple maggot on the apple trees. The fruit trees in the garden are small, so covering them was fairly easy. I have covered a 20-foot cherry tree with netting. I sewed a lot of netting together to make it big enough, but it keeps the birds away and prevents insect problems on my cherry tree.
Cultural control includes cultural practices that reduce pest establishment, reproduction, dispersal and survival. Choosing plants that the pest will not feed on is an example of cultural control. The adult Japanese beetle feeds on more than 300 plant species. The Japanese beetle grub feeds on turfgrass roots. We have too many host plants in the garden to choose this method.
Biological control includes predators, parasites and pathogens. Some birds prey on Japanese beetle adults, and skunk, raccoon, moles and crows prey on Japanese beetle grubs. The damage to turf by the latter group is unacceptable and should be avoided.
The winsome fly, Istocheta aldrichi and the tiphid wasp, Tiphia vernalis, are natural parasites of the Japanese beetle in Japan. Neither seems to be very effective in the United States at this time. Hopefully with more research, parasites will work better in the future.
There are a number of soil protozoa pathogens that have been found in both adult and larval Japanese beetles. The protozoa stress host insects but cause very little mortality.
Chemical control measures will be discussed in my next growing concerns column.