New York Agricultukal Experiment Station. 211 

 PLUM DISEASES. 



BLACK KNOT. 



(Ploiurightia morhosa (Schw.) Sacc.) 

 About 20 years ago plum growing was an important industry 

 in the Hudson Valley, particularly in Greene Co. About 1884 

 there was an epidemic of black knot which ruined most of the 

 plum orchards and so discouraged fruit growers that few have 

 had the courage to replant on a large scale. Another, but Hess 

 destructive epidemic occurred in 1891. At the present time the 

 Japanese plums are being planted quite largely. They are not 

 affected to an injurious extent by the black knot. On the 

 European varieties it is still very troublesome and an epidemic 

 may be expected whenever a favorable season occurs. It has prob- 

 ably spread but little during the past season. 



FRUIT ROT. 



(Moiiilia frudigena P.) 



The Hudson Valley plum grower has another serious enemy in 

 the brown rot of the fruit. In spite of the very dry season this 

 disease has been quite bad in some localities. At Millbrook, 

 Dutchess Co., it is reported to have destroyed two-thijds of the 

 crop; at Old Chatham, Columbia Co., 50 per ct. of the crop; at 

 Annandale, Ulster Co., Newburgh, Orange Co., and at Blauvelt, 

 Rockland Co., 25 per ct. It was also abundant in Westchester 

 Co., and occurred to a considerable extent in Greene and Rensso- 

 laer counties. 



LEAF BLIGHT OR " SHOT HOLE " DISEASE. 



This disease is commonly caused by the fungus Cylindrosporium 

 padi Karst., but Duggar^^ has recently shown that it may be 

 produced by Bordeaux mixture, especially if improperly pre- 

 pared ; by other chemicals and even by certain weather conditions. 



32Duggar, B. M. Peach Leaf-Curl and Notes on the Shot Hole Effect of 

 Peaches and Plums. Cornell Agr. Exp. Sta. Bui. 164. F. 1899. 



