ANNUAL REPORT, 1931 215 



Mcintosh Apples, Block A 



PERCENTAGE OF FRUIT SHOWING 



Treatment Insect Injury Scab 



Lime-sulfur 1 27 16 



Lead arsenate J 



Lime-sulfur 1 



Lead arsenate [ 1^ 24 



Lime j 



Sulfocide 1 



Lead arsenate \ 23 39 



Lime J 



Dry lime-sulfur 1 g yj 



Lead arsenate j 



Dry mix sulfur lime 1 o jg 



Lead arsenate J 



*Check 



Mcintosh Apples, Block E 



Flotation sulfur 1 je q^ 



Lead arsenate j 



Kolofog 1 13 5 



Lead arsenate J 



Lime-sulfur 1 jg 0.5 



Lead arsenate j 



**Check 110 35.0 



*A11 fruit dropped; practically 100 per cent of it scabby. 

 **55 per cent had more than one blemish. 



Similar results were secured on Baldwin. Scab was, however, less conspic- 

 uous on that variety and some differences in insect injury were noted, principally 

 due to the longer growing season of Baldwin. 



Control of Onion Thrips. (A. I. Bourne). The early season, marked by 

 relatively high temperatures and abundant rainfall, was favorable for the growth 

 of both seed and set onions, while the frequent and heavy rains offered less favor- 

 able conditions for the rapid development of thrips. The infestation throughout 

 the Connecticut Valley was comparatively light and somewhat lower than in 

 1930. No fields were observed where thrips caused serious damage. In most of 

 the fields of seed onions adjoining sets, the infestation was only moderately heavy, 

 while those isolated from sets were comparatively free from thrips. 



The seasonal development of thrips closely followed the normal except for a 

 rather heavy migration of winged adults from sets late in June which took place 

 during a period of unusually high temperature. 



The great migration of thrips from sets occurred somewhat earlier than the 

 date of the pulling of the set onions and coincided very closely with the date 

 when those plants had matured and before they had broken over and fallen. 



Studies of the effects of environment on thrips abundance in a field of seed 

 onions exposed on the north to sets and on the south to grassland indicated the 

 relative danger of early and heavy infestation from hoih. sources, because of the 

 opportunity for rapid increase offered by the sets and the excellent hibernation 

 quarters furnished by grassland. Examination of this field, at the time when the 



