22 BULLETIN" 684, U. S. DEPAETMENT OF AGRICULTURE. 



crop was shaken off. One tree, which appeared to be hopeless on 

 account of the number of cankers and was otherwise of small value, 

 was left untouched and recommended for removal. 



As soon as a few of the trees were free from rotted fruit the spray 

 outfit was started, so that each tree was sprayed almost as soon as 

 the diseased fruits, mummies, and cankers were removed. This 

 treatment so effectually checked the spread of the disease that com- 

 paratively few new infections occurred, although the season was an 

 exceedingly favorable one for the development of the rot, the loss 

 on many near-by orchards being 25 per cent and upward. The trees 

 were again sprayed with Bordeaux mixture on August 7. 



The varieties used in this experiment were the Jonathan, Ben 

 Davis, and Givens, all of which, and more especially the last named, 

 are quite susceptible to the disease. Yet at picking time the loss in 

 the case of the Jonathans was only 4 per cent of the crop, while that 

 of the other two varieties was but 1 per cent. In orchards in which 

 during previous years the disease had caused about equally as severe 

 losses as in this one, the losses during 1915 were at least 50 per cent, 

 even in the case of those which had been sprayed. In many un- 

 sprayed orchards the crop was a total loss. In the spring of 1916 

 the same orchard was again examined for cankers and mummies and, 

 as in the year previous, the first infected fruits and the sources of 

 these infections were removed. The task was quite an easy one in 

 1916, as the work of the two preceding years had nearly eliminated 

 the disease. Only two applications of Bordeaux mixture were made, 

 one early in July and a second about August 1. Throughout the 

 season the apples remained almost entirely free from rot, and ex- 

 amination of both dropped and picked fruit in the autumn revealed 

 so few specimens of infected apples that the damage was considered 

 negligible and impossible to compute on a percentage basis. 



In 1917 the orchard had received two sprayings for the preven- 

 tion of bitter-rot when visited by the writer on July 23. There was 

 practically no rot except on the one tree from which little effort had 

 been made to remove the cankers in previous years. This tree had 

 been infested with so many cankers that it had been marked for 

 removal, as already mentioned, but had finally been spared. The 

 disease had gained considerable headway on this tree and every fruit 

 appeared to be doomed. 



GENERAL SUMMARY. 



(1) Apple bitter-rot, caused by the fungus GlomereUa cingulata, 

 occurs in nearly all sections of the world where apples are grown, but 

 reaches its high point of destructiveness in the more southern apple- 

 growing sections of the United States. 



