48 MASS. EXPERIMENT STATION BULLETIN 369 



the new growth showed no spray injury, and on the trees sprayed with Hme- 

 sulfur the late growth was composed of large, flat, normal leaves typical of the 

 foliage on trees which received wettable sulfur throughout the season and in 

 sharp contrast to the small, malformed leaves which received the lime-sulfur 

 application. (See photograph on page 49.) 



The crop on the Baldwin trees was very light and uneven. Many of the trees 

 had no fruit and those which produced even a light crop bore most of the apples 

 on the west side of the trees, a possible reaction to the hurricane. The Mcintosh 

 trees on the other hand fruited heavily and the crop developed to good size and 

 excellent color. The record of the Mcintosh crop at harvest indicated that 

 liquid lime-sulfur at reduced strength was measurably safer to foliage without 

 losing its efifectiveness against scab. When lime-sulfur was diluted to half the 

 usual strength (1 gallon to 100) and combined with wettable sulfur, it checked 

 scab satisfactorily and caused no appreciable burn. Spray catalizer acted as a 

 protective agent when used with the lime-sulfur-lead arsenate combination and 

 in a large measure reduced the customary lime-sulfur injury to foliage. 



Control of Striped Cucumber Beetle. (W. D. Whitcomb, Waltham.) In the 

 experimental planting at Waltham in 1939, the striped cucumber beetle was 

 normally abundant, averaging about 40 beetles per hill on untreated cucumbers 

 and 10 per hill on untreated cantaloupes. More than 75 percent of the beetles 

 were found on cucumbers, thus further emphasizing the preference for this crop. 



In general, the influence of the beetle infestation on the yield of fruit was not 

 significant. Continued dry weather prevented the development of bacterial 

 wilt even in the presence of a larger number of beetles, and a heavy infestation 

 of melon aphid was responsible for a general infestation of cucumber mosaic. 



In these experiments, treatments were made seven times between June 17 and 

 July 15, while four additional applications were made between July 27 and 

 August 26 to protect the vines until yield records were secured. Undei these 

 conditions the most effective materials in reducing the beetle infestation were: 



Calcium arsenate-red copper oxide-flour-talc 10-6-10-74 



Copper rotenone-talc 4.75 percent copper and .8 percent rotenone 



Cube-talc 0.75 percent rotenone 



Calcium arsenate-talc 1-14 



Calcium arsenate-monohydrated copper sulfate-lime 10-20-70 



All of these dusts reduced the beetle population 80 percent or more on cucum- 

 bers, and 90 percent or more on the cantaloupes. 



Of these materials the calcium arsenate-red copper oxide and the calcium 

 arsenate-monohydrated copper sulfate were the most effective on cucumbers, 

 but the latter caused slight to moderate foliage injury and was much less satis- 

 factory. Applications of fibrous talc alone gave 79 percent protection but showed 

 the lack of a toxic ingredient, while wettable den is spray was ineff'ective. 



In direct comparisons copper oxychloride dust and calcium arsenate were more 

 effective against the beetle with talc as the carrier than with hydrated lime, but 

 a better yield was obtained from vines treated with dust in which lime was the 

 carrier. Calcium arsenate with red copper oxide was more effective on cucum- 

 bers, but calcium arsenate with copper zeolite was superior on cantaloupes, and 

 the yield from the cucumber vines dusted with the copper zeolite mixture was 

 the best. 



Dusts containing rotenone and those containing calcium arsenate were both 

 effective against the striped cucumber beetle; but better yields were obtained 

 where the calcium arsenate dusts were used and, since they are cheaper, they are 

 preferred. 



