EFFECT OF SOIL APPLICATIONS OF INSECTICIDES 11 



Onions 



Onions of the Brown Spanish variety were planted as sets in 

 rows at 8-inch spacings. The dates of planting were April 18, 

 1949, February 16, 1950, and March 9, 1951, and the onions were 

 harvested on July 28, 12 and 9, in the respective years. The tops 

 were removed and all rotted or unmarketable onions discarded 

 before weighing. The initial application of the insecticides did 

 not affect the growth or appearance of the onions, and none of the 

 treatments affected the yields. In 1950, however, wireworms de- 

 stroyed some of the sets and reduced yields in the untreated plots 

 and tended to reduce yields in those treated with ethylene dibro- 

 mide. No wireworm damage was noted in the plots treated with 

 aldrin, chlordane, or toxaphene, and these materials did not affect 

 the growth or appearance of the onions. 



Observations made in 1951 failed to reveal any differences in the 

 time of emergence or rate of growth of the onions, but the yield 

 in the ethylene dibromide plots was substantially reduced. In these 

 plots more than the usual number of onions were discarded be- 

 cause of fusarium rot, which was primarily responsible for the 

 low yield (table 2). 



Table Beets 



Table beets of the Detroit Short Top variety were seeded in 

 single rows 31 feet long on March 27, 1950, and beets of the De- 

 troit Dark Red variety on March 12, 1951. In 1951 yields were 

 obtained by weighing the beets and the tops from each row sep- 

 arately, but in 1950 only the beets were weighed. 



There was no significant difference between treatments in the 

 yield of table beets in either year. A tendency to low yields was 

 noted in the plots treated with toxaphene and aldrin in both 

 years, which was difficult to explain because there was no differ- 

 ence in the appearance or size of the plants between the treated 

 and untreated plots (table 2). 



SwEETPOTATOES 



Sweetpotatoes of the Porto Rican variety were planted in 1951 

 only, in soil where sugar beets had failed to germinate. The slips 

 were planted on May 16 in single rows 31 feet long at 2-foot 

 spacings. They were harvested on October 10. There were no 

 differences in the growth or size of the plants in the various plots, 

 although the yield tended to be lowest in those treated with 

 ethylene dibromide (table 2). 



Spinach 



Viroflay spinach was seeded in single rows 31 feet long on 

 March 19 and harvested on May 24, 1951. Yields were obtained 

 by making one cutting of the leaves at the ground level after they 



