6 BULLETIN 444^ U. S. DEPARTMENT OP AGRICULTURE. 



The disease appears to have originated in Wisconsin, but has 

 become estabUshed in Massachusetts, New Jersey, Oregon, and 

 Washington by transplanting diseased vines. 



The cause is not known. No evidence has yet been obtained to 

 indicate that it is produced by insects or fungi. 



It is suggested that the disease may be due to unbalanced nutri- 

 tive conditions. 



The disease is perpetuated from year to year in plants reproduced 

 vegetatively from diseased plants, not only in bogs where the trouble 

 originated, but also under somewhat more favorable conditions of cul- 

 tivation in localities in which the disease was unknown previously. 

 Observations made by Mr. Malde in Wisconsin and by a grower in 

 Oregon seem to indicate that the offshoots from plants affected with 

 false blossom tend to recover and become normal when transplanted 

 and grown under optimum soil and moisture conditions. 



To overcome the disease, optimum conditions for growth should be 

 provided, including good drainage, clean culture, and pruning. 



Where diseased plants are numerous, the bog should be scalped 

 and replanted with healthy vines. 



To prevent the further spread of the disease only vines known to 

 be absolutely free from it should be planted. 



