Question
willow leaves, web, an
I have a weeping pussy willow and there is an extremely small yellow bug that has been covering the entire top of the tree with webs. The leaves have begun to turn brown a the tree looks very unhealthy all in a matter of a week. I have tried to treat it with Seven spray and dust but it is not helping. Do you know what this might be?
Answersounds like spider mites. Mites are not insects but are more closely related to spiders. They are very small and not seen easily with the naked eye. They have piercing mouthparts that they use to suck plant sap. Their feeding results in speckling (formation of tiny yellow spots) on needles. Some needles may turn brown and drop off. With heavy infestations, fine webbing may be seen on the plant. Several seasons of heavy mite feeding may kill a Leyland cypress. Although most spider mites increase in numbers during hot, dry weather, spruce spider mites are cool-weather mites. Their populations peak during spring and fall, but drop dramatically during the heat of summer when predators feed on them.
To determine whether insecticide use is needed, it helps to know how many mites are present. Hold a white sheet of paper under a branch and strike the branch. The mites that are knocked off will be seen crawling around on the paper. If dozens of mites are seen per whack, serious damage can result. Continue to check population numbers at 7- to 10- day intervals. Pesticides labeled for homeowner use against spruce spider mite include insecticidal soaps and acephate + fenbutin oxide (Ortho Systemic Insect Killer or Ortho Orthenex Garden Insect & Disease Control Concentrate). Completely cover the foliage with the spray. As with any pesticide, read and follow all label directions and precautions before using. The Seven will not control the spider mites. Check with your local nursery for a miticide for spider mites.
