940 Populak Editions of Station Bulletins of the 



reaching all the tiny creatures at this time with a spray that would 

 be effective and at the same time safe to the tree made it almost 

 impossible to destroy all of the early broods and made repeated 

 treatments necessary — a time-requiring and expensive plan. 

 As far back as 1896, however, Dr. J. B. Smith of the New Jersey 

 Station recommended spring spraying with whale-oil soap just 

 as the buds begin to swell; and in 1899 Prof. Slingerland of Cornell 

 also urged treatment at this time and suggested kerosene emulsion 

 or kerosene and water as applications. In his tests these and other 

 materials for destroying the eggs did not prove successful and, 

 consequently, few attempts have hitherto been made to fight the 

 insect in this stage, as the eggs have been thought quite resistant 

 to any contact insecticide at a strength safe to use on foliage. 



The advent of lime-sulphur suggested new possibilities, and tests 

 were accordingly planned by this Station to determine the feasibility 

 of getting rid of the insects in the winter or early-spring stages and 

 to escape, thereby, the difficult task of summer control. 



These tests have now been continued for four 

 Successful years, and have proved very conclusively that 

 treatments. the psylla can be readily controlled by either of 

 two methods, each involving but one treatment, 

 or, at worst, by using both applications. For complete success, how- 

 ever, the treatments must be carefully made, and, particularly for the 

 destruction of eggs and young larvae in the spring, at just the right time. 



The treatments recommended — fall or early spring spraying 

 with nicotine preparations, miscible oils or soapy solutions to kill 

 the hibernating adult flies, and treatment with lime-sulphur just as 

 the cluster buds are beginning to spread, to destroy eggs and emerging 

 nymphs, can be made uniformly successful in isolated orchards, or 

 in communities where all growers unite in the effort. Where adjacent 

 orchards are neglected, however, it may be necessary to make sup- 

 plementary sprayings to control invaders from such unsprayed 

 plantations. 



During 1911, experiments were conducted by 

 Fall spraying the Station in the pear orchards of the Middle- 

 for adults. wood Farms, Varick, N. Y., to test the value of 

 fall spraying to reduce the numbers of over- 

 wintering adult psyllas or " flies." The orchard contained 800 

 Bartlett trees and had suffered severely from psylla injury during 

 the summer. Spraying began on December 6 and continued 

 at intervals, as weather permitted, for ten days, during which period 

 thousands of the insects were clustered on the untreated trees. 

 The insecticides used were tobacco extract, fish-oil soap, and lime- 

 sulphur used separately, and each of the others in combination 

 with the tobacco extract. 



The tobacco preparations and the soap solutions proved very 

 effective, but lime-sulphur at the strength for dormant spraying was 



