Fungous Diseases of Garden Plants. — 143 



leaf surface. All authorities are agreed that spraying repeatedly 

 with Bordeaux mixture will prevent the disease, or at least 

 greatly mitigate its attacks. 



Much more to be dreaded, because more regular in its visits, 

 more prevalent, and apparently less understood, is the " /m/"- 

 j/f?/" disease, ''early blightl' ox '' Macrosporinm disease." It at- 

 tacks the leaf and stem, but never 

 the tuber. The accompanying illus- 

 tration will give an idea of its general 

 appearance. The attacks may begin 

 at any time after the plants are a 

 few inches high, but usually the first 

 signs of it are noticed at the ap- 

 proach of real hot weather in July. 

 Grayish-brown spots appear on the 

 older leaves, and the affected parts 

 soon become hard and brittle. The 

 disease progresses quite slowly; the 

 spots become gradually larger ; the 

 edges of the leaflets curl up, and 

 after a time the larger part of the 

 leaf surface may be brown, with- 

 ered, and brittle. In a month, more 

 or less according to the weather, all 

 the leaves may have succumbed, and the stalks alone stand — 

 yellowish-green — leafless for awhile, to perish shortly after from 

 starvation. The tubers are checked in growth, and remain un- 

 dersized. Cool and wet weather usually puts a stop to the further 

 progress of the disease. I have not been able to check it, in a 

 perceptible degree, by even persistent spraying with fungicides. 

 The " bacterial blight,'' which is characterized by the sudden 

 wilting and the premature death of the affected plants, and causes 

 the young tubers to decay or their flesh to become discolored, 

 has already been mentioned as a disease of cucumber, melon, and 

 other vines. It also attacks tomato and egg-plants. Its ravages 

 have been more serious in Southern latitudes than at the North. 

 Planting on new and uninfected land is the only precaution that 

 can be recommended. 



The "potato scab," a disease w'ith which every grower is 

 familiar, can be prevented by the use of clean seed and clean 

 soil. The fungus lives in the humus of the soil, as well as on 

 the tuber. Therefore land which has produced scabby potatoes 

 in previous years, or has been fertilized with manure from stock 

 fed with scabby potatoes, should not be used for potato-growing. 

 The use of commercial (concentrated) fertilizers in place of stable 

 manure can be recommended as a safe precaution. If the soil 

 is free from the scab fungus, clean potatoes may be grown even 



Potato Leaf Spotted with 

 Early Blight. 



