ANNUAL REPORT, 1937 



61 



infestation and also indicated practically no survival of parasites from liberations 

 3 years previous. Late-summer twig collections showed that the fruit moth had 

 built up a heavy infestation, and considerable damage to midseason and late 

 varieties was found in many orchards. One of the orchards in which twig infesta- 

 tion was heaviest and in which the most damage was found in fruit at harvest 

 was located alongside a large planting of quinces. While injury to the peach crop 

 was extensive, the quince crop was ruined. This further confirmed the belief 

 that quinces are highly flavored by oriental fruit moth and constitute a serious 

 threat to any peaches grown in the immediate vicinity. 



Potato Spraying Experiments. (A. L Bourne.) Flea beetles appeared early and 

 were unusually abundant throughout most of the season over the entire State. 

 Even in well-sprayed fields, they proved difficult to control. 



Leafhoppers appeared late in the summer and were not abundant enough to 

 cause any damage. Potato aphids during the hot, dry weather in July threatened 

 serious outbreaks, but timely applications of nicotine checked the pest so suc- 

 cessfull}' that no serious injury was caused even in fields of early varieties such as 

 Irish Cobbler. 



In the experimental plots, different insecticides were tested on the standard 

 late-season variety, Green Mountain. Twelve applications of Bordeaux, mixture 

 were made between June 10 and August 27. Two rotenone compounds, nicotine 

 tannate, a pyrethrum extract, and calcium arsenate were tested in combination 

 with 5-5-50 and 5-3-50 Bordeaux mixture in the applications from July 9 to 

 August 12. The ranking of the different materials on the basis of flea beetle con- 

 trol was as follows: 



With 5-5-50 Bordeaux 



With 5-3-50 Bordeaux 



DX (pyrethrum) 



520 



Check (Bordeaux only) 



355 



In both combinations the rotenones were about equally effective and decidedly 

 ahead of all othei treatments. Both were much more effective in the low-calcium 

 Bordeaux. Calcium arsenate gave equally good protection in both combinations. 

 Nicotine tannate showed to better advantage with 5-3-50 Bordeaux, and the 

 effectiveness of DX, the pyrethrum extract, was greatly increased in this com- 

 bination. The fact that all the materials gave better control with the 5-3-50 

 Bordeaux would indicate that their action may be somewhat inhibited by the 

 excess lime of the 5-5-50 combination. 



Very general and often severe burning of foliage resulted from the July sprays, 

 many of which were applied at extremely high temperatures. While these frequent 

 applications were unavoidable because of the prevalence of flea beetles, the 

 injury seriously checked the growth of the plants and the set of the tubers. In 

 many cases the plants never fully recovered from this setback so that, on the 

 whole, the yields were comparatively light, as shown in the following table. 



