ORCHARD INSECTS OF THE PACIFIC NORTHWEST 



25 



Control of the woolly aphid in cankers caused by the perennial 

 canker is not always accomplished by the usual sprays. The Oregon 

 Agricultural Experiment Station has recommended trimming out all 

 cankered bark early in the summer, allowing the wounds to heal 10 

 to 14 days, and then applying (with a brush or a paint gun) a mix- 

 ture of 1 part of nicotine sulphate (40 percent nicotine) and 6 parts 

 of tree paint. The wounds should be repainted annually. Informa- 

 tion about tree paint may be secured from the Oregon Agricultural 

 Experiment Station. 



Control of the aphids on the roots is extremely difficult. The most 

 practical method is to keep the trees in a thrifty, vigorous condition, 

 by means of proper cultivation and fertilization, so that they can 

 withstand the drain caused by these insects. Applications of tobacco 

 refuse about the roots, fumiga- 

 tion with carbon disulphide, and 

 other remedial treatments have 

 been tried, but are not always 

 successful. Paradichloroben- 

 zene, recommended for control- 

 ling the peach borer, has been 

 used with some success for the 

 woolly aphid, particularly on 

 old trees. It should be applied 

 in the same manner as for the 

 peach borer (p. 52), at any time 

 during the summer or fall, at 

 the rate of three fourths ounce 

 to 1 ounce per tree. 



TREE HOPPERS 



Young orchards containing 

 alfalfa or clover cover crops are 

 subject to the attacks of several 

 species of tree hoppers, among 

 which the buffalo tree hopper 

 (Ceresa bvbalus Fab.), the green 

 clover tree hopper (Stictocephala inermis Fab.), and the dark-colored 

 tree hopper (C. basalis Walk.) (fig. 29) are the most injurious. The 

 injury is caused by the wounds and scars made by the female in lay- 

 ing her eggs in the bark of the trees (fig. 30). These scars are cut by 

 the female with her ovipositor, and maj be roughened and ragged or 

 clean-cut, longitudinal slits, depending on the species making them. 

 The injury rarely extends more than 6 or 8 feet above the ground, and 

 young trees are most often attacked. Frequently the growth of such 

 trees is seriously retarded. Injury is practically confined to the cur- 

 rent season's growth and to 1-year-old wood, but the old scars persist 

 for some years. Apple and pear trees are the most subject to injury, 

 although peach, cherry, plum, and quince are occasionally affected. 







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Figure 28.— Nodular roots resulting from attack by 

 the woolly apple aphid. 



LIFE HISTORY 



The whitish, cylindrical eggs of the tree hoppers are about one 

 tenth inch long, and from 6 to 20 of them are placed side by side in 

 each slit, the ends usually being visible. They are deposited during 



167469°— 33^ 



