54 MASS. EXPERIMENT STATION BULLETIN 339 



14. The spray was applied at a temperature of 85° — 87° F. Within three hours 

 after the plots were sprayed the vines were comparatively clear and the ground 

 beneath green with aphids. No further contact sprays were necessary through- 

 out the remainder of the season. 



The protracted drought during July and early August was not favorable 

 for high yields, a duplication of the conditions which prevailed in 1935 with 

 similar results. The yield in the experimental plots was as follows: 



Yield 

 Materia] Bii9hels per 



acre 



Bordeaux mixture 5-5-50 439.1 



*Nicotine tannate 464 .4 



*Derris (rotenone) 463 . 7 



*Cubor (rotenone) 457.3 



*Niagron (rotenone) 456.8 



*Ku-ba-tox (rotenone-pyrethrum) 422.7 



*Calcium arsenate 420. 8 



*Combined with Bordeaux Mixture 5-5-50 



With flea beetles the outstanding insect pest and in the absence of potato 

 diseases, the higher yield in the nicotine-tannate and rotenone plots is believed 

 to be due largely to the protection furnished against incipient attacks of leaf- 

 hoppers and potato aphids and reflected the superior appearance of the plants 

 in those plots throughout the growing season. 



Three different commercial brands of copper sprays designed for use on potato 

 were compared with 5-5-50 Bordeaux mixture. Eleven applications of each were 

 made. The yield and relative position of each are represented as follows: 



Yield 

 Material (Bushels per 



acre) 



Bordeaux mixture (5-5-50) 469.3 



Basic copper sulfate (Sherwin-Williams) + lime 448.4 



Potato spray (General Chemical Company) 432.1 



Oxo-Bordeaux (Ansbacher-Siegle Corp.) 416.8 



Plants in the plots sprayed with the last two materials showed a considerable 

 amount of leaf burn which shortened their growing period. Whether the pro- 

 longed growth in the Bordeaux and basic copper plots was due to the protection 

 afforded by excess lime is not known. In view of the comparatively poor show- 

 ing of basic copper sulfate in 1935, it would appear that the lime present was 

 an important factor contributing to this improvement. 



Insecticides for the Control of European Corn Borer. (A. I. Bourne.' 

 Life history studies have shown that young, newly hatched corn borer larvae 

 feed for a short period directly on the leaves of their host plant. On corn the 

 young larvae migrate to the narrow spaces between the unfolding leaves in the 

 central whorls of the main stalk and tillers. After the second or third instars 

 the caterpillars become borers and enter the stalks or the young developing 

 ears. The use of insecticides against this insect is based on the habit of the 

 young larvae of feeding externally during the early period of their growth. 



In cooperation with the Federal European Corn Borer Laboratory in New 

 Haven, Conn., the department ran field tests with three contact sprays in half- 

 acre plots of sweet corn on two farms in Hampden County. Each material 

 was run in quadruplicate with a corresponding number of unsprayed areas. 



