New York Agricultural Experiment Station. 439 



influence of the weather conditions as described must obviously 

 vary greatly according to seasonal conditions, but there is little 

 doubt that ice storms, cold, driving rains, and strong winds do, under 

 certain circumstances, greatly reduce the number of " flies " and 

 thereby lessen the extent of egg deposition. 



STATION EXPERIMENTS TO DETERMINE THE SUSCEP- 

 TIBILITIES OF HIBERNATING "FLIES" AND 

 THEIR EGGS TO SPRAYING MIXTURES. 



FALL AND EARLY WINTER SPRAYING AGAINST HIBERNATING ADULTS. 



During 1911, experiments were conducted in the pear orchards 

 of the Middlewood Farms at Varick, Seneca county, to determine 

 the value of the fall spraying as a means of reducing the numbers 

 of " flies " going into hibernation. The plantings comprised about 

 800 twenty-year-old Bartlett pear trees which had been severely 

 injured by psyllas during the summer. Spraying commenced on 

 December 6, and was continued at intervals, as weather permitted, 

 until December 18, during which period thousands of the insects 

 were clustered on the untreated trees. The spraying mixtures 

 used in these tests were tobacco extract (40 per ct. nicotine), fish-oil 

 soap and lime-sulphur solution, used separately, and each of the 

 latter two in combination with the tobacco extract. The nicotine 

 preparations were diluted at the rate of three-fourths of a pint 

 of tobacco extract (40 per ct. nicotine) to one hundred gallons of 

 water, or lime-sulphur, 32° B., in the proportion of one gallon to 

 eight gallons of water. When the tobacco extract was used alone 

 three pounds of fish-oil soap was added to give spreading and adher- 

 ing properties. Fish-oil soap was applied in the proportion of one 

 pound to five gallons of water. The concentrated lime-sulphur 

 wash was used at strength for dormant spraying, one gallon of the 

 concentrate to eight gallons of water. 



The tobacco preparations and the soap solutions proved very 

 effective. Lime-sulphur wash at dormant strength did not cause 

 marked reductions in the numbers of psyllas, but with the addition 

 of nicotine very effective results were obtained. On warm days 

 which followed the sprayings few "flies" were detected and it was 

 estimated that less than five per ct. of the original infestation of 

 the psylla existed on the trees. During the following spring but 



