REPORT OF THE SOCIETY 105 



speH at longer intervals like 2^/2 weeks. Spray before a wet spell and use a fine 

 spray which will cover both sides of the leaves. Dusting is as good as spraying 

 for potatoes in most localities. To control potato-chewing insects it is necessary 

 to add calcium arsenate or lead arsenate to the spray or dust. It is not 

 necessary here to deal with the preparation of Bordeaux mixture cr dust, but 

 any grower desiring information will be gladly accommodated if he will write 

 to Macdonald College. 



9. Finally greater care must be taken in digging, handling and storing 

 potatoes. It is unfortunate that an excellent yield is sometimes spoiled in 

 its last stages by bad handling. 



SCLEROTIAL DISEASE OF THE POTATO 

 By O. W. Lachaine, B.S.A. 



Sclerotial diseases of the potato have been reported from many countries 

 "within recent years. That known as "stalk disease" caused by Sclerotinia 

 sclerotiorum is common in the West of Ireland and in the northern damper 

 parts of England and Scotland. Growers believe that it is the most serious 

 potato disease in these districts next to "Late Blight". A similar disease 

 caused by the same fungus attacks tomato, artichoke, bean, cucumber, carrot, 

 turnip, corn, pea, cabbage, cauliflower, hemp and chicory (Cotton, A. D.) 

 in England. Bisby has reported a sclerotial disease of sunflower from Mani toba 

 which is common also in Quebec and elsewhere. MacAlpine found a sclerotia 

 disease of potato in Australia, which he attributed to 8. sclerotiorum; Carpenter 

 one in Hawaii caused by S. Rolfsii, and Pole Evans reports one from South 

 Africa. During the summer of 1921 the writer found 10 per cent infection 

 of a 4 acre field of potatoes in Restigouche County, New Brunswick, and four 

 other fields of 3 or 4 acres had from 1 per cent to 2 per cent infection. 



\ 

 Symptoms 



The first symptom noticed by the writer, August 24, 1921, was a blackish 

 zone extending from the surface of the soil to about 5 inches in height giving 

 it somewhat the appearance of "blackleg". By rubbing, the cortical tissues 

 were easily removed. Three weeks later, on September 16th, the outer 

 necrotic tissues were dried out while the leaves were yellowed. Above and 

 below the necrotic area the stem tissues were still green. On splitting open 



