THE PEACHES OF NEW YORK 173 



Self -boiled lime and sulphur, if it does not wholly prevent infections, at 

 least alleviates the trouble. 



Peach-growers in New York are much plagued by a mildew yet suffer 

 small loss from it, though the disease greatly injures peach-foliage in some 

 regions. The delicate, white or grayish powder, giving the name " powdery 

 mildew," consists of the spores and mycelium of a fungus (Sphcerotheca 

 pannosa (Wallroth) Leveille) which attacks the leaves of several species 

 of Prunus causing them to cvirl and crinkle and sometimes to drop. It 

 occurs most often when there are sudden changes in temperature. When 

 treatment is necessary, the self -boiled lime-sulphtir mixture is used. 



In common with all tree-fruits, the peach is attacked by crown-gall 

 {Bacterium tumefaciens Smith and Townsend). In New York crown- 

 gall seldom greatly injiires old trees but nursery plants are sometimes 

 girdled by the galls, seriously injuring them. Badly diseased young plants, 

 therefore, should not be planted. The galls are tumor-like structures, 

 usually at the juncture of top and root, which vary from the size of a pea 

 to that of a large egg, forming at matiirity rough, knotty, dark-colored 

 masses. Neither preventive nor cure is known. Planting diseased trees 

 is not a safe practice, nor shoiild the peach be set in ground known to have 

 recently had trees badly infected. The raspberry is a common carrier of 

 crown-gall and should not be planted as an inter-crop in a peach-orchard. 



The peach suffers more or less from an excessive flow of gum. This 

 gumming is usually a secondary effect of injuries caused by fungi, bacteria, 

 insects, frost, sunscald, and mechanical agencies. There is a good deal 

 of difference in the susceptibilities of varieties to this trouble, sorts having 

 hard wood suffering less than those having soft wood. There is less 

 gumming, too, on trees in soils favoring the maturity of wood, under con- 

 ditions where sun and frost are not injurious, and, obviously, in orchards 

 where by good care the primary causes of the diseases are kept out. 



INSECTS ATTACKING THE PEACH 



The peach has its full share of troublesome insects, entomologists 

 listing about forty species, at least half of which are either destructive or 

 annoying in New York. The peach cannot undergo hardships and once 

 it is beset by parasites, it does not prosper. No small part of the peach- 

 grower's time, therefore, is spent in combating the insect-pests of his trees. 

 The several pestiferous species vary greatly in importance, the peach- 

 borer probably holding first place in destructiveness. 



