Answer: Whoa! Herbicides are weed and vegetation killers! You really don't want to use them on your fruit trees! Lichen and moss grow naturally on fruit trees in the Pacific Northwest. The plants are not parasitic; do not take nutrients from the tree, nor dothey cause a great deal of injury. Mostly they just look ugly. Annual spraying of lime-sulfur (Bordeaux), a fungicide that protects trees from scab, will also discourage the growth of lichen and moss. After a few treatments, the plants will slough off the branches of the trees. If you have leaf curl on your plums, you've probably got aphids. They suck the plant juices, resulting in curling leaves. You can encourage beneficial ladybugs and lacewing insects to visit your garden and feast on the aphids by not spraying insecticides, and by having a host of flowering plants in your yard to attract them. Watch your plum trees carefully and try to remove the leaves that are aphid infested. You can use an insecticidal soap like Safer's if you must treat the aphid problem with a chemical.
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