Bamboo pit scale

[nutsenf]

Hi everybody, about two weeks ago I noticed black spots on the stem where side-stems originate (apologies if my terminology is not correct) and little bumps on the stems themselves. An entomologist at the University of Florida determined that the bamboo suffers from the so-called bamboo pit scale. I found some pictures on this and other sites, but no suggestions for how to treat it. Any advice would be greatly appreciated.

[CaroleMeckes]

Here is some info about scale from the American Bamboo Society website: http://www.bamboo.org

Pit scale insects, of which there are more than 50 species, are very common on bamboos. One of them (Asterolecanium bambusae) infests Bambusa in Southeast Asia, where it sucks sap from the culm sheath and stems. It has a waxy covering, making it difficult to control by insecticidal sprays. Systemic insecticides are much more effective on this scale. Unfortunately both it and the related Asterolecanium miliaris have slipped into the U.S. where they infest Bambusa.

Another pit scale is Bambusapis hemispherica, found in Phyllostachys in China and Japan. It has one or two generations per year, and the female adults and nymphs suck sap from the twigs and stipes of the bamboo. Its relative, B. bambusae, has been found on Bambusa multiplex in Florida.

Another type of scale, the armored scale, has 60 species that suck bamboo sap. One of the more notorious is Kuwanaspis pseudoleucaspis, which infests Phyllostachys in China and Japan. It has also gotten into the U.S. and is common on Phyllostachys; here it is known as thread scale. It has two generations per year, preferring the older culms and wet, shaded sites. This scale is worse in dense, over-mature groves, where the nymphs and females feed on culm sap, and when present in large numbers can reduce the vigor of the plant and make the culms commercially worthless. In Asia they are controlled naturally by parasites and ladybeetles, and culturally by thinning out the older culms, and by culm-cavity injection of systemic insecticides. Other species of Asian thread scale present in the U.S. include K. vermiformis (which will infest A. gigantea), K. howardi (infests Bambusa), and K. hikosani, which can infest various bamboos (observation by Adam Turtle).

Other scales found on bamboo include Unachionaspis bambusae, found on Phyllostachys in China, where it has three generations per year. These scales suck sap from the young leaves in the lower crown, and heavy infestations can cause partial defoliation. In Asia it is kept under control by parasites and predators. Odonaspis penecillata is found on various bamboos in China and has one generation per year, over-wintering as an adult. Female adults and the nymphs suck sap from the culms and branches. It has also been imported to the U.S.,where it has been found on Bambusa multiplex. Another import, O. secretus, has been found in the U.S. on Pseudosasa japonica.