New York Agricultural Experimrxt Station. ll()7 



were rare while the eanc knots were plentiful, and it was plain 

 that no relation existed between the two kinds of knots. 



On August 16 we again visited the plantation for the purpose 

 of studying the disease on the new canes. 'The knots were already 

 abundant on the new canes and in all stages of development. It 

 was at once observed that the knots were intimately associated 

 with anthracnose. Some of the canes were considerably 

 spotted 'with anthracnose and such canes were badly knotted. 

 Where anthracnose was most abundant^ the knots were most 

 abundant; and where there was no anthracnose, there were no 

 knots. One apparent exception to this rule was found. A cane 

 bearing a single incipient knot appeared to be entirely free from 

 anthracnose. This cane was placed over night in a moist cham- 

 ber, and the following morning a typical anthracnose spot was 

 seated on the very summit of the forming knot. Upon micro- 

 scopic examination the spot was found to be fruiting profusely 

 and was undoubtedlv anthracnose. The knots were most abun- 

 dant near the base of the cane and the anthracnose, also, was 

 most abundant on that part of the cane. Occasionally canes 

 were found bearing maii}^ anthracnose spots, but no knots. All 

 the anthracnose spots did not produce knots by any means. 



Each knot seemed to start in an anthracnose spot. At first a 

 longitudinal crack appears across the anthracnose spot: this 

 crack elongates, becomes brown, and as the knot increases in 

 size the outer bark is gradually thrown off, exposing masses of 

 rough spongy tissue, which takes forms very suggestive of pop- 

 corn. 



We have seen the same kind of knots, also, on the variety 

 Thompson on the Station grounds; and there existed the same 

 intimate relation between the knots and anthracnose as in the 

 case of the Cuthberts. It is plain that this cane knot of rasp- 

 berries is caused by the anthracnose fungus. Possibly Bailey's 

 blackberry cane knot^^ may have the same origin. 



Rust {Puccinia peckiana Howe. Syn. Cwonm nitens Schw.). — 

 Rust is a common and destructive disease of black raspberries 



'"Cornell Uiiiv. Agr. Exp. Sta. Bui. 99:427-428. 



