POTATO DISEASES IN 1907. 

 W. J. Morse. 



In comparison with the conditions prevailing for several 

 years, particularly with those of 1906, the season of 1907 

 presents a decided contrast with regard to the development of 

 the various Maine potato diseases. All through the eastern 

 part of the State, low temperatures prevailed during the entire 

 growing season. Planting and hoeing were delayed from 2 

 to 3 weeks and spraying largely interfered with. The wet 

 weather at digging time and immediately preceding, greatly 

 increased the amount of loss from rot on unsprayed or improp- 

 erly sprayed fields. 



Early Blight. — Alternaria solani, which was very prevalent 

 and destructive during the dryer season of 1906, was seen only 

 on a few fields, late in the season — little or no damage resulting 

 from this cause. 



Late Blight. — Phytophthora infestans. For several seasons 

 preceding 1907 this fungus has been responsible for very little 

 damage in Aroostook County. This has been due partly to the 

 almost universal practice of spraying and partly to the prevail- 

 ing weather conditions. A careful search over several hundred 

 acres the last of August, 1906, failed to show a single leaf of 

 well defined late blight. In 1907 it was first seen by the writer 

 August 8 at Ft. Fairfield, where the disease was well distributed 

 and had already destroyed the entire foliage on one field. Very 

 soon all but the most thoroughly sprayed fields were severely 

 attacked. Several days of bright, dry weather beginning the 

 third week in August decidedly checked the epidemic in most 

 localities. Wet weather about September 1 started the blight 

 again with renewed vigor, this time lasting until frost came. 

 Continued wet weather through September resulted in a large 

 amount of rot following blight except on the most thoroughly 

 sprayed fields. 



