April, 1914.] Report on. Raspberry Curl or Yellows. 283 



Occurrence of Raspberry Curl. Raspberry curl is found main- 

 ly on Cuthbert, Marlboro, Golden Queen, Early King and Her- 

 bert, the varieties being susceptible in the order named. Cuthbert 

 and Marlboro are probably the most susceptible varieties, and at 

 present are being discarded entirely for commercial purposes. 

 The disease is found occasionally in other varieties of red raspber- 

 ries, but very rarely on black caps or purple kinds. 



Besides occurring in Minnesota and New York, it has been 

 reported in Connecticut and Colorado. The writer has found 

 this disease in Ohio, Michigan, Cahfomia, and Washington, and 

 it is probable that this same trouble occurs in Canada, Massachu- 

 setts, Pennsylvania, and Kansas, while not improbable that it 

 could be found in most localities where the red raspberry is grown 

 extensively. 



Fig 2. Current year's growth showing premature flowering. 



Economic Importance. The writer has made a study of rasp- 

 berry curl in Ohio, especially in Lucas and Cuyahoga counties, 

 two localities which have grown raspberries extensively. In 

 these regions red raspberries were at one time a very important 

 crop. Today there is grown only one-fifth the acreage of eight 

 years ago. This falling off has been due, as far as can be ascer- 

 tained, entirely to the raspberry curl disease. A number of grow- 

 ers conservatively estimate an annual loss of $200 per acre due to 

 this disease. 



Symptoms of Raspberry Curl. Generally the disease does not 

 make its appearance until the second 3^ear after planting, while 

 sometimes three season elapse before it becomes severe enough 

 to attract attention. When it once appears in a plant, it invari- 

 ably reappears annually to a greater or less extent and as long as 



