100 



FUNGI AND FUNGICIDES 



are carried to new places on the plant during rains, and 

 there they germinate and start the disease anew. M;m\ 

 of them are probably blown from plant to plant and 

 field to field by the wind, and thus the disease is spread. 

 All of these spores are the so-called summer spores 

 (conidia) ; no true winter spores have yet been found. 

 It is supposed that the mycelium is perennial, carrying 

 the fungus through the winter. 



Treatment. Easpberry foliage is very sensitive to 

 the corrosive action of fungicides, so that care in treat- 

 ment is necessary. The most successful results in pre- 

 venting this disease, as yet obtained, are those reported 

 by Mr. W. J. Green, of the Ohio Experiment Station, 

 who used a dilute Bordeaux mixture. His directions 

 are as follows : "The first application should be made 

 early in the spring before the leaves open, at which time 

 the spraying should be very thoroughly done. The sec- 

 ond application should be made soon after the young 

 canes appear above ground, and the spray directed to 

 them alone. The third application is to be made about 

 two weeks from the date of the second, taking the same 

 precaution to spray the young canes only. The fourth 

 and last application should be made just previous to the 

 time of blooming, in the same manner as advised for the 

 second and third sprayings. Raspberry leaves are very 

 tender and the mixture injures them slightly, but not 

 enough to preclude its use, especially if some care is 

 taken to keep it off the leaves of the bearing canes. The 

 leaves on the young shoots of the current season's growth 

 are not so easily harmed, hence no pains need be taken 

 to keep it off them." 



Mr. Green also reports good results from the ammo- 

 niacal copper carbonate solution, "with even less harm 

 to the foliage, but, all things considered, the dilute 

 Bordeaux mixture is preferred." It is advisable to cut 

 out and burn all fruiting canes each summer as soon as 

 the crop is gathered. 



