ANNUAL REPORT, 1942 37 



in the Connecticut Valley showed 20 to 30 percent pupation by the first week of 

 May, and the first moths emerged on May 12. Emergence increased steadily to 

 a peak on June 8 with a gradual reduction during the next 10 days. Coupled with 

 the comparativeh small carry-over of borers because of the light infestation in 

 1941, this early moth emergence, in advance of the development of the corn, 

 resulted in a comparatively light infestation of early market sweet corn although 

 somewhat heavier than in 1941. There was, however, a substantial build-up 

 during the summer and a more normal infestation of the corn which matured in 

 late August and September. 



In the experimental plots the insecticidal applications, based on the first 

 appearance of young, newly hatched larvae, were made on June 10, 15, 20, and 

 25. Precipitation during that period, while it totaled 2.8 inches of rainfall, was 

 so well distributed that there was very little interference with the treatments. 



Because of the war emergency and the limited supply of rotenone available, 

 the sale of this material for use on corn was forbidden so that the field tests were 

 confined to a study of the value of nicotine bentonite and dual-fixed nicotine. 



Results from spraying with nicotine bentonite (14 percent nicotine) indicated 

 a considerable increase in protection when 3 pounds per 100 gallons were used as 

 compared with 2 pounds, but no advantage when more than 3 pounds were used. 

 Protection was good in all cases. Dual-fixed nicotine dust again furnished good 

 protection. 



From the commercial standpoint the contrast between the corn harvested from 

 treated and untreated plots was more pronounced than can be indicated by figures. 

 Many of the ears scored as "infested" in the treated plots contained very small 

 borers which had hatched after the last application but had scarcely penetrated 

 the husks. A large proportion of such ears could be salvaged. Infested ears 

 from the check plots, however, contained many large, fully developed borers; 

 destruction of the kernels was extensive; and most of the ears were worthless. 



Potato Spraying Experiments. (A. I. Bourne.) The experimental plots were 

 planted May 4 and 5. The plants made an early start, received no serious set- 

 back to their steady growth during a long growing season, and were for the most 

 part alive and green until killed by frost on September 28 to 29, 146 daj's from 

 the date of planting. 



Flea beetles appeared in large numbers as soon as the plants were up, uere 

 very abundant throughout June and early July, and again from late July until 

 mid-August. There were no serious infestations of other insects. 



The plots were given 11 applications of spray between June 5 and August 25. 

 In view of the war emergency and the possible shortage of copper for agricultural 

 purposes, special attention was devoted to a study of different strengths of bor- 

 deaux, and one plot was given a complete schedule of 2 J^-2 J^-50 bordeaux mixture 

 to determine the protection furnished against disease and insect attack by the 

 reduced dosage. 



Flea beetle injury was measured by the number of leaf punctures per square 

 inch of leaf area, and varied inversely with the strength of the bordeaux mixture. 

 In every case the addition of calcium arsenate to the bordeaux mixture reduced 

 the number of feeding punctures. The reduction was greatest (one half) in the 

 plots which received the half-strength bordeaux, and was only slight in the plots 

 which received the standard 5-5-50 bordeaux, indicating that the addition of the 

 arsenical was an important factor whenever the strength of lime in the bordeaux 

 was reduced. 



Sufficient protection was furnished by all the different strengths of bordeaux to 

 keep the plants alive and vigorous throughout the growing season, and scarcely 

 a trace of blight was noted. In an adjoining plot which was sprayed with a com- 



