18 



BULLETIN 703, U. S. DEPARTMENT OF AGRICULTURE. 



best results. It was to be expected that the sprays and dusts used on 

 the spring crop of 1916 would show better results than those used 

 on the spring crop of 1917, as in 1916 their application was con- 

 tinued longer after harvesting began. On the fall crop of 1916, 

 however, where harvesting was completed 13 days after the last 

 spraying, the spraying apparently had little or no effect in some in- 

 stances in reducing injury. In this connection it should be stated, 

 however, that the plants used as checks produced but a small amount 

 of fruit, partly because they were badly injured by Phlegethontius 

 larvae when small. Comparisons of results from sprayed and check 

 plants may, therefore, not be indicative of the true value of the 

 sprays. 



It is to be noted that the Earliana variety of tomato showed a 

 higher percentage of injured fruit than did either the Globe or the 

 hybrid. 



The diagrams (figs. 2-5) show the number of tomatoes produced 

 each week by Earliana and Globe plants set out in the springs of 

 1916 and 1917, part of these being sprayed with arsenate of lead 

 and the others serving as a check. The percentage of the number 

 of fruit showing injury is also given. The diagrams show that the 

 Earliana produced the greater portion of its crop sooner than did 

 the Globe and that in 1916 both varieties produced their crops within 

 a shorter period of time than in 1917, there being a pronounced 

 " second crop " during 1917. 



200 or 

 40$ 



100 or 

 20# 



Yig. 2. — Diagram, prepared from weekly totals during harvesting season, showing number 

 of tomatoes of the Earliana variety and percentage apparently injured by the tomato 

 fruitworm in 1916. Spaces between horizontal lines represent 100 in case of total 

 number of tomatoes, and 20 in case of percentage wormy. Vertical lines represent , 

 weeks. The solid line represents the total number of tomatoes from the unsprayed 

 check ; the dotted line, the percentage of check wormy ; the line of dashes, the total 

 number of tomatoes from plants sprayed with arsenate of lead ; the line of dots and 

 dashes, the percentage of sprayed tomatoes wormy. 



