8 BULLETIN lli, U. S. DEPARTMENT OF AGRICULTUEE. 



SprayiiiK- 



Thorough spraying has been found in all localities to reduce rot 

 and improve the keeping quality of the fruit. In New Jersey and 

 on Long Island, where there is always considerable loss from fun- 

 gous disease before picking and where spraying has been practiced 

 in some cases for 10 years, thorough spraying has been found 

 profitable and no injury to the vines has been observed. 



Experiments were conducted with the Early Black variety at 

 Whitesbog, N. J., during 1917 to determine the times at which 

 Bordeaux mixture should be applied in order to control fungous dis- 

 eases most effectively and economicalh\ Blast, early-rot, and a 

 storage rot, all due to Guignardia vaccinii Shear, were the principal 

 caus?es of loss on this bog during the year. Bordeaux mixture of 

 the formula 4-4—50, with about 1 pound of resin-fishoil soap, was 

 used throughout the experiments. 



A single thorough application of Bordeaux mixture after the blos- 

 som buds had begun to open increased the total yield by more than 

 10 per cent (from 173 to 192 bushels per acre) by controlling blossom 

 blast. Two applications before blossoming were no more effective 

 than one. An application immediately before the spring reflow 

 showed no effect in the control of fungi. No trace of the spray was 

 observed on the vines when the water was removed. The applica- 

 tions before blossoming had no effect in reducing the rotting of the 

 fruit after picking. 



Protection of the berries from infection during the first month 

 of their growth resulted in very satisfactory control of both field 

 and storage rots. This was accomplished by two thorough applica- 

 tions, one near the close of the blossoming period (before all the 

 petals had fallen) and another two weeks later. By these applica- 

 tions alone the total yield was increased, the rot at picking time was 

 reduced from more than 20 per cent to less than 2 per cent, and stor- 

 age rot from 6.7 per cent to 1.9 per cent. These two sprays applied 

 at the proper time effected a saving of 44 bushels of marketable 

 cranberries per acre, or one-fourth of the crop. Any delay in mak- 

 ing the first application after blossoming resulted in a marked in- 

 crease in both field rot and storage rot. 



A third application after blossoming was of no increased benefit 

 in these experiments. It must be repeated, however, that early-rot 

 was the only fungous trouble of importance on this bog ; furthermore, 

 the berries were picked before the middle of September. It is doubt- 

 ful whether two applications after blossoming will give satisfactory 

 control with all varieties or where other diseases, such as bitter-rot, 

 are concerned. A similar series of experiments with cranberries of 

 the Centennial variety in New Jersey during 1917 gave unsatisfactory 



