234 AGRICULTUEAL EXPERIMENT STATION. [Jan. 



spores. The leaves then lie upon the ground until spring, 

 when the winter spores germinate and infect the new season's 

 foliage. 



It is evident that much of the harm done by this rust in 

 rendering the trees unsightly and in causing premature 

 defoliation can be avoided by thoroughly cleaning up and 

 burning all the fallen leaves before snow falls, while the 

 winter spores are still incapable of germination. 



Antliracnose of Chestnut. — Since the cultivation of the 

 chestnut is beginning to receive attention in some quarters, 

 and bids fair to be attended with considerable success, it 

 may be worth while to mention a fungus which, from its 

 prevalence on wild chestnuts about Amherst, seems likely to 

 prove troublesome to the cultivated plant. This fungus, 

 which must be known as Marsonia ochroleuca (B. & C), 

 causes an antliracnose of the leaves in the form of small, 

 thin, bleached spots, on which the spore pustules are formed. 

 These spots are sometimes so abundantly developed as to 

 cause the leaves to shrivel and die ; and the fungus may be 

 expected to do much greater harm to trees growing under 

 the artificial conditions of cultivation. 



The Black Knot of the Plum. — The study of this disease 

 has been continued during the past year, both theoretically 

 and practically. Some trees in an advanced stage of the 

 disease have been put in charge of this department for treat- 

 ment, and progress has been made in both lines of study. 

 But the results obtained have not been so complete as was 

 hoped for, partly on account of the limited material at my 

 disposal and partly because a large amount of time was 

 required for other studies reported here. Therefore it seems 

 best to reserve the results obtained until they can be com- 

 bined with those hoped for during the coming year, in a 

 more complete and hence more satisfactory account. 



Diseases of Tobacco. — This department has communicated 

 with some leading tobacco growers in the Connecticut valley 

 during the past fall, with a view to the investigation of the 

 various diseases or affections to which tobacco is subject in 

 the curing shed. These are known chiefly under three 

 names, white vein, pole sweat and pole rot. How far these 

 names represent afiections due to distinct causes it is 



