36 MASS. EXPERIMENT STATION BULLETIN 398 



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type of spray proved much more satisfactory and gave better penetration than 

 the conventional hollow-cone spray. 



Ladybeetles and other natural enemies of thrips did not appear in the fields 

 in sufficient numbers to keep step with the rapid increase in thrips during late 

 July, and there was no evidence of the presence of the fungus disease which usuaUy 

 appears in the fields in seasons when thrips are unusually abundant. 



The Value of Control Measures to Supplement the Standard Spray Program 

 for Apple Pests in Massachusetts. (A. 1. Bourne.) The study of proposed substi- 

 tutes to replace or supplement present standard materials and practices was 

 shaped to give special attention to replacements for materials subject to curtail- 

 ment because of the war emergency. This involved a determination of the value 

 of certain non-arsenical compounds and a study of more effective timing of late 

 season applications. 



In a study of the effect of pyrethrum on overwintering larvae of the codling 

 moth in their cocoons on the trees, a pyrethrum-kerosene solution was applied 

 to the rough, flaky bark of the main trunk and base of the larger limbs of a small 

 block of apples, early in April while the trees were still in dormant condition. 

 These trees received no other application for codling moth control. Collections 

 of both drops and samples from these trees showed less than one-fourth as n^any 

 apples with codling moth stings and entrances on the treated trees, as on the 

 checks. The pyrethrum-oil application caused no damage to bark nor retarda- 

 tion of seasonal development. It apparently had no permanent repellent action 

 to codling moth larvae as indicated b\' approximately the same number of larvae 

 collected in chemically treated bands, from both sprayed and untreated trees, 

 at the end of the growing season. 



This treatment eliminates the necessity for most of the scraping of loose bark 

 from the trees and should prove very effective in penetrating the winter cocoons 

 of larvae hibernating in piles of prop poles. These often attract large numbers of 

 larvae and, since they are usually collected in piles at the edge of the orchard, 

 serve as potential centers of infestation often entirely ov'erlooked by the grower. 



In orchard tests to determine the value of various non-arsenicals for codling 

 moth control, one application of a fixed nicotine (14 percent nicotine) replacing 

 lead arsenate in the 4th cover spray reduced codling moth damage to 1.5 percent 

 as compared with 4 percent following the present standard schedule. Fruit 

 from unsprayed checks in this block showed 19.4 percent injury by codling moth. 



Where fixed nicotine replaced lead arsenate in the 4th cover spray and was also 

 applied in mid-August, samples of fru't at harvest showed less than 6 apples per 

 1,000 damaged by codling moth. 



A modified schedule in which a commercial pyrethrum-rotenone combination 

 was applied in the 2d, 3d, 4th, and mid-August sprays practically eliminated 

 codling moth damage. Lead arsenate was used with this combination but at 

 reduced strength. 



An application of fixed nicotine between the 2d and 3d cover sprays to furnish 

 protection between June 12 and July 9 gave increased protection against codling 

 moth, although the effect was not so pronounced as would be the case in a year 

 when codling moth presented a more serious problem. 



All of these materials were used with the wettable sulfur for scab control, proved 

 entirely compatible with the fungicides, and held scab to less than 1 percent dam- 

 age while samples from unsprayed trees showed 92 percent scabby fruit. 



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

 warm, dry weather in April stimulated corn borer activity and, as in the previous 

 season, promoted early pupation of the overwintering larvae. Field collections 



