Edamame offers the home gardener a tasty and nutritious crop of green soybean pods, but humans aren't the only ones who enjoy munching on the plant. A number of animals and insects eat the leaves and pods of the edamame plant and could negatively affect its productivity if not dealt with. There's good news, though; edamame naturally avoids some of the worst pest attacks thanks to its early harvest.
If you find evidence of insects eating the leaves of your edamame, it could be one of a number of creatures, including Japanese beetles, stinkbugs and bean leaf beetles. Luckily, the damage from these leaf munching insects usually does not damage yield or quality of edamame directly. But stinkbugs can open the plant to disease when they pierce the leaves to feed. If a pest is eating the pods, it could be corn earworms, also known as soybean pod worms. Along with stinkbugs, these creature are usually not present in large numbers until late summer. Other attacking pests include wireworms, spider mites and cucumber beetles.
While these creatures may not leave visible evidence of their feeding right away, they can cause serious damage to edamame plants. Aphids feed on soybean sap, which damages the plant's photosynthetic abilities and can spread viruses. Aphids quickly reproduce and colonize leaves in large numbers. These tiny green insects, which can number in the thousands on a single plant, can reduce yield by more than 50 percent when infestation is severe.
Deer, elk and rabbits may feed extensively on pods and leaves when the soybean plant is young. As the plant reaches maturity, slugs may feast on leaves and pods, and birds may nibble on the pods as well. You can identify slug feeding by the small holes and trail of slime left on the plant surface. Large animal pests can be devastating to a mature edamame crop. A barrier or fence protecting the plant may be necessary in such a case.
Many of the harmful leaf-eating insects that enjoy soybeans become most rampant in late summer. It can be very beneficial to plant edamame early enough to avoid harvesting after mid-August. In a North Carolina State University study, a soybean crop planted on May 1 saw no stinkbugs, but the June 2 planting saw a significant number.
To combat aphids, use insecticidal soap or other insecticides marketed for soybean aphids. Generally, these foliar sprays suppress the aphids for a temporary period of seven to 14 days. Application is most important from bloom to early pod formation when populations are on the rise.