202 PEACH LEAF CURL*. ITS NATURE AND TREATMENT. 



leaving- unsprayed trees for comparison. The trees of the sprayedT^lock, 

 it is stated, were very nice and straight and made a good growth, and 

 there was no curl, it being hard to find a leaf affected, while growth 

 started well and continued thrifty throughout the season. The 

 unsprayed trees on the other hand curled so badly that many were 

 crooked and stunted, not attaining the height of the sprayed trees 

 within a foot, and a good many were worthless. The treated trees 

 were sprayed twice in the month of March, 1897. They note that 

 Bordeaux mixture, to do its work properly, should be on the trees 

 for seven or eight days without rain. 



SUMMARY. 



(1) Peach leaf curl haG a world-wide distribution, occurring in every 

 region in which the peach is grown. In humid localities it is a leading 

 hindrance to peach culture, and in portions of the Pacific coast States 

 it has greatly limited the extent of the industry. 



(2) The orchard losses from peach leaf curl vary from a small amount 

 of fruit to the entire crop, while in many instances young trees are 

 killed. The national losses from this disease will amount to $3,000,000 



annually. 



(3) Curl is caused by a parasitic fungus known as ^a?(>«.sc?<.s^^/(?rm-fm«, 

 the ravages of which are largely dependent upon the atmospheric con- 

 ditions prevailing while the trees are leafing out. Rains and cold 

 weather at that time tend to increase the severity of the trouble by 

 favoring the growth of the parasite and interfering with the proper 

 functions of the host. For these reasons orchards near large bodies of 

 water and in low or damp situations are more subject to curl than 

 those in dry regions or in elevated situations. 



(4) Most of the spring infections of peach leaves are due to the 

 spores of the fungus and not to a perennial mycelium, as formerly 

 held, hence the efficacy of sprays. 



(5) Curl was first successfully treated in Calif ornia during the period 

 from 1880 to 1885, the success depending upon the application of 

 fungicides to the dormant trees. The disease was not successfully 

 treated in Europe for ten years after its prevention in the United 



States. 



(6) The copper sprays are now found to be more effective than the 

 sulphur or other sprays first used. Of the various sprays experi- 

 mented with, Bordeaux mixture, in the proportion of 5 pounds copper 

 sulphate, 5 pounds lime, and 45 gallons of water, gave the best results, 

 the equal weights of the copper sulphate and lime being most effective 

 when the mixture is applied shortly before the opening of the blossom 

 buds. When it is desired to increase the durability of a spray by 

 increasing the proportion of lime, the application should be made 

 earlier or equal proportions of copper and lime should be maintained. 



