ANNUAL REPORTS. 273 



the tubers. On the leaves it produces brown spots which 

 often show faint concentric rings. Plants having this dis- 

 ease are often affected with the late blight also. 



Late Blight (PhytophtJiora infestans De By.). The late 

 blight has damaged the potato crop to a greater or less ex- 

 tent in every portion of the state from which information 

 has been received. Even sprayed fields have not been en- 

 tirely free from the disease. The early stages show black 

 spots at the tips or edges of the leaves. On the under side of 

 the leaf at the margins of these spots may be found a slight 

 whitish growth. It is here that the spores of the fungus 

 are produced. These spores spread the disease rapidly. 

 The black spots enlarge, soon covering the entire leaf. 

 The tubers from diseased plants often rot badly in storage, 

 especially when stored in large piles. It is not certain to 

 what extent this rotting is due to the above fungus. There 

 is considerable evidence, however, that the fungus may pass 

 the winter in the tubers. 



Potato Scab (Oospora Scabies Thaxt.). This disease 

 has been of common occurrence the past year, damag- 

 ing many fields to the extent that few or no market- 

 able tubers were obtained. Potatoes affected with the dis- 

 ease become peculiarly roughened and scabbed. At the 

 time of digging the fungus sometimes shows as a slight 

 whitish mold on the scabbed surface. The fungus can re- 

 main in the ground for several years and potatoes planted 

 where the disease existed the year previous are almost cer- 

 tain to be infected. 



Dise:ases o]? Cucumbers and Muskmelons. 



Downy Mildew or Blight [Plasmopora cubensis (B. & C.) 

 Humpf.]. The blight appears early in August as large, 

 brown, angular spots on the leaves^ These increase in num- 

 ber rapidly and the leaves soon die. The summer spores are 

 produced on the under surface of the leaf on branching 

 stalks. The winter stage of the fungus has never been 

 found. The disease has been very common this year and 



