ANNUAL REPORT, 1934 41 



Percentage Percentage of Fruit Showing 



Treatment of Clean Injury From: 



Fruit 



Curculio Codling Moth Scab 



Apple Dritomic 88.2 4.0 5.7 1.1 



Magnetic sulfur 91.7 3.0 4.3 



Mulsoid sulfur 70.5 16.5 13.6 0.2 



300 mesh sulfur + wetting agent 85.8 5.6 4.5 3.2 



Sulcoloid 94.5 0.4 2.2 1.1 



Lime-sulfur 78.1 1.3 15.7 3.5 



Flotation sulfur 88.4 0.9 8.9 0.3 



Check 10.4 52.0 34.4 50.4 



All the products controlled scab very satisfactorily. In the summer sprays 

 after the calyx, a casein spreader was added to the lime-sulfur-lead arsenate 

 sprays. It should be noted that the commercial wettable sulfurs held scab to a 

 lower figure than did lime-sulfur to which the spreader had been added. These 

 results were also noted in the tests in the commercial orchards. Apparently 

 the efforts to lessen the danger of burning from the lime-sulfur-lead arsenate 

 combination also materially reduced its efficiency against scab. The combination 

 of finely divided sulfur and wetting agent was not quite as effective against 

 scab as were the commercial products but it gave very satisfactory control, and 

 this product with lead arsenate held insect pests to as low a figure as did the more 

 expensive commercial products. 



Control of Striped Cucumber Beetle with Derris and Pyrethrum Dusts. When 

 both commercial and home-made dusts containing the derris equivalent of .4 

 to .6 percent rotenone, and a pyrethrum-sulfur dust with a .05 percent pyrethrin 

 content were applied directly to the beetles in the laboratory, all were dead or 

 dying 4 hours after application. Copper-arsenate-lime dust (20-10-70) killed 

 60 percent of the beetles in 44 hours, while all untreated beetles lived 10 days or 

 longer. When untreated beetles were confined with dusted plants, the dusts 

 protected the plants from injury and the majority of the beetles were dead after 

 15 days. Copper-arsenate-lime was slow in becoming effective but was very 

 satisfactory at the end of the experiment. Pyrethrum-sulfur dust was the least 

 effective material. Undusted plants were killed in three days. 



In the field 7 applications of these dusts were made to melons, cucumbers, and 

 summer squash. Fresh applications of dust killed many of the beetles and pro- 

 tected the plants from injury until they were washed off, although the greatest 

 interval between rains during this period was 5 days. Derris-sulfur dust and 

 copper-arsenate-lime dust caused slight injury to melon vines during excep- 

 tionally hot weather, and this caused a slight decrease in the yield. Yield records 

 of melons and cucumbers indicated that the application of these dusts did not 

 noticeably interfere with pollination. 



Control of White Apple Leafhopper with Pyrethrum and Derris Dust. A 20-80 

 pyrethrum-clay dust applied from both sides at the approximate rate of 1 p3und 

 per tree of medium size on August 30 reduced the second generation of the white 

 apple leafhopper on Mcintosh from an average of 18.66 per leaf to 3.07 par leaf. 



On September 10 in another orchard where the infestation averaged 10.18 

 hoppers per leaf, an application of derris-pyrethrum-clay dust (10-15-75) re- 

 duced the average number of hoppers to 7.08 per leaf; derris-clay dust (12^-87^), 

 to 4.21 per leaf; and pyrethrum-clay dust (30-70), to 2.16 hoppers per leaf. The 

 number of dead hoppers per square foot on cloth spread under representative 

 trees was: derris-pyrethrum dust, 10.45; derris dust, 45.43; and pyrethrum dust, 



