-Hit! THE MONTHLY BULLETIN. 



Clearly G. volekei present a special problem in methods of control. The writer has 

 conducted some experiments with this end in view and which are hero briefly 

 recounted. 



As most of the larvae are feeding on the leaves in the early fall it should be possible 

 to greatly reduce their numbers by defoliation just after the fruit is picked. Accord- 

 ingly some plots were sprayed with crude oil emulsion and lime-sulfur solution at 

 full winter strength, also strong solutions of nitrate of 

 soda with caustic soda and sodium sulfide. These materials 

 were applied during the last week in October and soon 

 after the fruit was picked. As defoliaters, crude oil 

 emulsion and lime-sulfur solution were not successful, 

 the shedding date being only slightly ad\anced by their 

 use. The caustic solutions with sodium nitrate proved 

 too strong, killing the foliage too quickly to allow of 

 shedding. 



From these results it appears that a successful defoli- 

 ating spray is in itself a problem. In order to be success- 

 the ?I app 1 lt 3 'leat-min S in°g f"l as intended in the case of G. volekei the defoliating 

 case - bearer, some- action will have to be very rapid. The fruit is seldom 

 what enlarged. (Orig- entirely removed from the orchards before the middle of 

 ma ' October and hibernation begins in November. 



The sprayed plots were inspected at intervals during the fall and winter. These 

 observations led to the conclusion that the hibernating larvae were practically as 

 abundant on the crude oil and lime-sulfur plots as on the checks. (The nitrate and 

 lye plots were located in a portion of the orchard quite free from the insect.) On 

 the crude oil plot some of the cases were found to be penetrated and the larvre killed. 

 The percentage of killing was, however, much too low to effect control. Standard 

 crude oil winter spraying is even less likely to be effective on account of the lower 

 concentration, 12 per cent against 15 per cent in the experiment. 



There remained one other method of attack, namely, the use of some contact 

 insecticide early in the spring or when the larva? were leaving hibernation. Some 

 previous work with nicotine sulfate 5 suggested nicotine as probably the most promising 

 material. 



On March 28, 1917, the first larvae were found feeding on the young foliage. A 

 few of these were treated in the laboratory with nicotine sulfate at strengths of 

 1 to 800 and 1 to 400. The results of this experiment were promising so some plots 

 were sprayed on April 5, with the following formula: 



Nicotine sulfate 3 pounds 



Flour paste (made with S pounds flour) 8 pounds 



Milled sulfur 12 pounds 



Water to make 200 gallons 



The plots treated with this formula included those receiving the oil and lime- 

 sulfur experimental spraying and a third plot, just adjoining, which received only the 

 standard winter spraying with crude oil emulsion. A second nicotine spraying with 

 practically the same formula was applied to these plots about May 2. 



General observations indicate that there has been a great reduction in the numbers 

 of C. volekei within the nicotine-sprayed plots. The actual fruit counts as recorded 

 in the accompanying table substantiate these observations to a marked degree, espe- 

 cially when the natural distribution of the species is taken into consideration. 



"Nicotine Sulfate for Codling Moth Control, Annual Report of the Horticultural 

 Department, Yakima County, Wash., 1916. 



