Also called Peking willow or tortured willow, globe willow’s (Salix matsudana) distinctive lime green leaves, sweeping branches and a spreading, rounded habit make it an attractive specimen. Though tolerant of a range of cultural conditions, globe willow is susceptible to attacks by harmful pests like flatheaded borers. Borers often infest trees that have been infected with frothy flux, a disease that causes the inner bark to ferment and froth, or on trees that have been weakened because of mechanical damage or poor cultural problems.
Chemical Treatments
You can treat borers by applying foliar insecticidal sprays once when adult insects first emerge, and again about three weeks later. Insecticide might also be put on the trunk and large branches, three times, every three weeks. A root drench could be applied to dominate borer larvae. Based on Texas A&M; University, insecticides applied externally to the leaves, branches or trunk should contain ingredients like phosmet or carbaryl, while root drenches should consist of imidacloprid. Always follow the manufacturer’s directions when applying chemical controls.
Worming
Borers might be destroyed by hand in a procedure called worming. Locate the borer holes, which are normally accompanied by sawdust and happen around the bottom 2 feet around the tree, and carefully extend the holes using a knife. Insert a cable within the tree to stab and kill any borers within the tree. Be careful to not too wound the bark, since this can invite infection into the tree.
Trap Logs
Trap logs are logs that are put near pest infestations and then later removed and burned once insects have left their initial host. Logs could be coated with a sticky paste, like tanglefoot, to trap the borers, but this isn’t vital. Logs should be placed in the sun, either vertical or lying down, close to the infested willow. Trap logs are helpful for heavy infestations, because they may entice large amounts on insects from the tree.
Prevention
A wholesome tree is not as prone to fall prey to borers. Globe willows do best in a bright, full-sun place with well-draining, moist soil in U.S. Department of Agriculture plant hardiness zones 5 to 10. Painting a wash of insecticidal wash and lye once or twice a month around the back of a wholesome tree can help deter egg-laying feminine borers. Don’t plant globe willows close borer host trees, like crab apples (Malus spp.) , service berries (Amelanchier spp.) or hawthorns (Crataegus spp.) . Clean up fallen branches and debris from across the tree, to avoid insects from hiding there.