ORCHARD INSECTS OF THE PACIFIC NORTHWEST 



51 



fruit. Injury by the mites may prevent the fruit buds from forming, 

 or at least may weaken them, causing a small crop or small fruit the 

 following year. This injury is often much more serious than is 

 apparent. All of the three species discussed on page 16 occur on these 

 trees. 



CONTROL 



Control is similar to that on apple and pear trees (p. 18). 

 If it is necessary to use sulphur sprays to control brown rot, 

 special applications 

 for red spiders 

 should not be nec- 

 essary. Summer 

 sprays of oil must be 

 applied before July 

 for the best results. 

 Later applications, 

 besides being less 

 effective, cause the 

 bloom on the fruit 

 to become spotted, 

 and this detracts 

 from its market val- 

 ue. Sulphur sprays 

 do not have this ob- 

 jectionable feature; 

 and if control has 

 not been attained 

 by the 1st of July, 

 sulphur sprays 

 or dusts should be 

 used. 



RUST MITE 



The rust mite 

 (Phyllocoptes schlech- 

 tendali Nal.) causes 

 prune leaves to curl 

 longitudinally and 

 become russeted or 



Figure 61. 



of young peach tree severely injured by the peach borer. 

 About one half natural size. 



silvered. The fruit 



may also be russeted. Control is the same on prune trees as on apple 



and pear trees (p. 21). 



PEACH BORER 



Peach borers are very serious pests of prune and peach trees, as 

 well as apricots and plums and occasionally cherries. The injury 

 occurs chiefly in the crown and roots of the trees, where the borers 

 tunnel beneath the surface, feeding on the inner or growing layer of 

 bark.. Young trees may be completely girdled and killed (fig. 61), 

 and older trees are frequently so weakened that they become subject 

 to other insect pests or to diseases. The presence of borers in the 

 trees is often first indicated by a quantity of gum at the base of the 

 trunk, mixed wdth dirt and frass. Poor condition of the trees may 

 also indicate the presence of the borers. Trees should be examined 



