New York Agricultural Experiment Station. 125 



sary to use the poison twice. On July 14 young " bugs " were so 

 numerous on Series I and III, that it was absolutely necessary to 

 poison them to prevent serious injury to the plants. At the same 

 time there were but a few on Series II, and even a week later there 

 were so few that it was a question whether it was worth while to 

 poison them. 



The explanation of this seems to be the fact that Series II was 

 sprayed with bordeaux a week earlier than Series I and some of 

 the young " bugs," which were hatching about that time, were killed 

 by feeding on the heavily-sprayed foliage. It is unlikely that they 

 migrated to the unsprayed plants because they were too young to 

 migrate. Similar observations were made in 1902 but interpreted 

 differently. (See Bui. 221, p. 245.) Whatever the true explanation 

 of it may be the fact is established that plants thoroughly sprayed 

 with bordeaux mixture are much freer from " bugs " than are un- 

 sprayed plants. 



About July 10 flea-beetles were quite numerous for a few days 

 and again about September i they were considerably in evidence, 

 but at no time did they materially injure the plants. However, their 

 work was more noticeable on the unsprayed than on the sprayed 

 plants. 



There was no injury whatever from early blight, Alternaria solani 

 and certainly none from drought. Nevertheless, some of the plants 

 on all the rows were slightly affected with a browning of the leaf 

 margins, the cause of which we were unable to determine. This 

 was first observed July 1 1 before the plants were a foot high and con- 

 tinued to be noticeable throughout the season. The leaves were 

 slightly curled and the margins brown. The worst-affected plants 

 died prematurely. The damage done was not great anywhere and 

 was least on the rows sprayed every two weeks. It could not have 

 been due to arsenic injury because it appeared before any arsenic 

 had been used. There was, however, slight arsenic injury on the 



