ANNUAL REPORT, 1946-47 35 



2d cov'er spray, all the sprayed rows received lead arsenate 2 pounds + fungicide. 

 In addition row 1 received DDT 3^ pound (actual); row 2 received DDT 1 pound; 

 and row 7 received DDT 2 pounds. Row 5 was left as a check. In the emergency 

 A spray and the 3d cover, the sprayed rows received the DDT as in the 2d cover, 

 but lead arsenate was omitted. In the 4th cover, lead arsenate 2 pounds + 

 fungicide was used, but no DDT. 



Because of frost damage, the yield on the check row of Mcintosh was too light 

 to be worth considering, so that the fruit on Cortland variety was checked. 



Codling moth was not as severe a pest as usual in many of the orchards in 1946, 

 but in the DDT blocks it was practically nil (about 3 apples in 500). The heavy 

 dosage of DDT (2 pounds actual) + lead arsenate (2 pounds) in the 2d cover 

 spray evidently cut curculio damage materially. This conformed with results 

 of tests in other orchards. The effectiveness of DDT was also reflected in the 

 protection against apple maggot and miscellaneous apple pests, all of which 

 were reduced to a mere trace; actually only a matter of an occasional apple per 

 bushel. It was also encouraging that in a season of unusual severity of scab, the 

 combination of DDT with wettable sulfur fungicide not only proved compatible 

 but gave excellent protection of the fruit from scab. 



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

 The first brood, corn borer infestation in Massachusetts was very light in 1946 

 and occurred somewhat later than usual. 



Cold, windy weather which prevailed through most of May appeared to be 

 very unfavorable for moth activity. Early plantings ot corn developed rather 

 slowly, and without doubt many moths in the field emerged before corn was up 

 or was of attractive size. This was certainly true of material in the emergence 

 cages. Probably many moths died without depositing eggs, whicTi seems to be 

 borne out by the insignificant infestation on early sweet corn since there was a 

 moderately heavy carryover and almost no winter mortality. 



Throughout most of the State damage by first-brood larvae was negligible 

 even in untreated fields. Severe drought from mid-June to late July may have 

 contributed one factor, since considerable rolling of the leaves occurred in many 

 fields and egg masses are easily dislodged, especially when rolling is accompanied 

 by hot, drying winds, such as occurred in 1946. The growth of corn was slowed 

 down and early plantings were late in maturing. Many fields planted by mid- 

 April or earlier, and breaking ground by late April, did not mature until early 

 August. 



The second brood was also somewhat delayed and in general was not serious. 



In the field tests, applications were made at 7-day intervals. Evidently this 

 was too far apart for securing best results from derris, although it appeared to be 

 satisfactory for the other materials. Ryanex both as a spray and as a dust gave 

 very satisfactory control and caused no injury. Applications ot DDT and DDD 

 were followed by slight burning. 



Of the sprays, Ryanex, DDT (1 pound actual), and DDD (1 pound actual) 

 gave 98-99 percent control. Derris (4 percent rotenone) gave 95.5 percent clean 

 corn. Of the dust materials, DDT (3 percent) gave practically complete protec- 

 tion, Fixed Nicotine Dust (4 percent nicotine) 97 percent, and Ryanex 94 percent. 



Potato Spraying Experiments. (A. I. Bourne.) The plots were planted May 9 

 and the plants made normal and satisfactory progress throughout the early season. 

 The plots were partially submerged by the heavy rains in late July when 4 to 5 

 inches of rain fell within about two days' time. Rains thereafter kept most of 



