Report of the Mycolocjist. 49 T 



tures the skin of the tubers while they are growing. This trouble 

 was common in the eastern portion of Long Island in 1895. 



(8) Fusarium acuminatum E. & E., a new species of fungus, 

 has been found on potato stems at Canandaigua, N. Y. It is 

 probably parasitic. 



' Introduction. 



On Long Island potato growing is one of the leading industries 

 and potato diseases consequently assume a proportional impor- 

 tance. 



The season of 1895 on Long Island was probably about an 

 average one for potato diseases. Some diseases were more de- 

 structive, while others were less destructive than usual. 



The bacterial disease which causes a watery rot of the young 

 tubers and suddenly wilts the tops by rotting the stem near the 

 surface of the soil, has been rare. Upon good authority I am in- 

 formed that in some seasons past, this disease has done much 

 damage. 



The potato scab, caused by the fungus Oospora scabies, which is 

 so troublesome in many parts of the United States, is not at all 

 common on Long Island. Its absence is to be attributed chiefly 

 to the facts that the soil is sandy and devoid of lime and that very 

 little barnyard manure is used. The fertility of the soil is main- 

 tained, for the most part, by the use of commercial fertilizers. 



The greater part of the damage to potatoes here is caused by 

 the two diseases known as early blight and late blight. Of these 

 two, the late blight is much the better knowil. This disease ap- 

 pears in warm, moist weather in mid-summer. It first attacks the 

 foliage. The leaves turn black and die. If the weathef con- 

 tinues warm and rainy whole fields may go down in a few days. 

 Later in the season the tubers become affected with a foul-smell- 

 ing rot. The cause of the disease is a parasitic fungus, Phi/toph- 

 thora infestans. The co/rly blight is not affected to any extent by 

 weather conditions. It appears every year and continues its dep- 

 redations throughout the entire life of the plants, whether the 

 weather be wet or dry. It attacks the foliage only, producing 

 32 



