APPLE LEAF-SPOT CAUSED BY SPHAEKOPSIS' MALORUM. 53 



TREATMENT. 



Since 1892, when Alwood 13 first recommended Bordeaux mixture 

 as a preventive for apple leaf-spot, other writers have advocated the 

 same method of treatment. The prevention of this disease has been 

 one of the most striking results of various spraying experiments and 

 demonstrations conducted by the Bureau of Plant Industry. Waite, 

 in 1901, in connection with bitter-rot experiments in Virginia, con- 

 trolled the disease with two applications of Bordeaux mixture. His 

 recommendations in Farmers' Bulletin No. 243, p. 19, are based upon 

 this work. Similar results were obtained by Scott 14 in Virginia in 

 1905. In the spraying demonstrations in the Ozarks during 1906 and 

 1907 the writers found that the spraying ordinarily necessary for the 

 protection of the fruit from fungous attacks a will usually control this 

 leaf trouble without any additional treatment. During both seasons 

 unsprayed trees were shedding their leaves by August 1 and were 

 completely defoliated by the middle of September, while the sprayed 

 trees remained in full foliage until the first killing frost. (Compare 

 PL IV, figs. 1 and 2.) In addition to the injurious effect upon the 

 trees this premature defoliation caused the fruit to be small and of 

 poor quality as compared with that from sprayed trees. An average 

 barrel of Winesaps from sprayed trees contained 612 apples, while 

 731 from unsprayed trees in adjacent rows were required to fill a 

 barrel. 



For the control of this disease alone, without reference to the 

 diseases of the fruit, an application of Bordeaux mixture should be 

 made in the spring a week or ten days after the petals have fallen, a 

 second application four weeks later, and a third about four weeks 

 after the second. Three applications are necessary only in exceed- 

 ingly wet seasons in sections where the disease is severe. Ordinarily 

 two treatments, one about three weeks after the petals are off and the 

 other four or five weeks later, are sufficient. 



A weak Bordeaux mixture, such as 3 pounds of copper sulphate and 

 3 pounds of lime to 50 gallons of water, is effective in controlling this 

 disease, Bordeaux mixture of full strength not being required. h 



a For a combination treatment for the leaf-spot disease, the diseases of the 

 fruit, and the codling moth, see Farmers' Bulletin No. 283, pp. 41-42. 



6 For various formulas and methods of preparing Bordeaux mixture, see 

 Farmers' Bulletin No. 243, pp. 5-10. 



121— v 



