SAN JOSE SCALE

A and B, Infestation on fruit; C, typical damage to new growth; D, a small cluster of scales (greatly magnified).

SAN JOSE SCALE

The San Jose scale is a tiny insect that sucks the sap from the wood, leaves, and fruit of apple, pear, peach, and other fruit trees. It occurs throughout the United States. Large numbers of scales lower the vitality of the tree and may gradually kill individual branches or even the tree itself. The mature female insect is yellow and about the size of a pinhead. It lives under a protective covering that is formed over it as it grows. Small reddish discolorations often are found at the point of feeding, particularly on new, tender wood and fruit. Heavily infested trees have a roughened appearance. The insect remains in one place except during the first few hours of its life and the short time adult males are active. The tiny, newly emerged young, called crawlers, move around on the tree and are sometimes blown or carried to trees some distance away. Partly grown scales survive the winter better than very young or mature ones. The generations, which overlap greatly, number one or two in northern fruit areas and three or four or more farther south.

In some areas, particularly the Midwest, another insect the Forbes scale may be confused with San Jose scale. The general appearance, seasonal history, and habits of the two scales are similar.

Control: Spray the trees early in the spring, before the buds open, with a petroleum oil emulsion. Dilute it to provide 4 percent oil in a spray for use in the Pacific Northwest and 3 percent oil in other areas. Parathion, one-half pound of 15 percent wettable powder per 100 gallons, in two or three or more summer spray applications will also control San Jose scale effectively and do away with need for the early spring application of oil.

Forbes scale, if present, can be held in check by the treatments used for San Jose scale.

Parathion is a dangerous poison; all safety precautions noted on the label should be observed in using it.