New York Agricultural Experiment Station. 423 



The practice of clean culture and the removal and destruction of 

 the rough bark left the " flies " with few opportunities of escape 

 from applications of contact mixtures. Miscible oils, nicotine 

 preparations and soapy solutions were effective sprays against the 

 psylla adults. Homemade oil-emulsions were less satisfactory, 

 which may have been owing to varying percentages of oil in the 

 mixtures, caused by imperfectly prepared emulsions. 



The best means of killing the " flies " is spraying during a period 

 of warm weather, preferably in November or December, or during 

 March or early in April. The most satisfactory mixture, from the 

 standpoints of safety to fruit and leaf buds and effectiveness against 

 the insect, is three-fourths of a pint of tobacco extract (40 per ct. 

 nicotine) in 100 gallons of water to which are added from three to 

 five pounds of soap. 



Eggs about to hatch and newly emerged nymphs succumb to an 

 application of the lime-sulphur solution. By postponing the dormant 

 treatment for the San Jose scale until the blossom cluster-buds 

 are beginning to separate at the tips, very effective work can be done 

 against the eggs. The lime-sulphur should be used in the proportion 

 of one gallon of the concentrate, 32 B., to eight gallons of water. 

 In some tests of other contact sprays the miscible oils, oil emulsions, 

 weak dilutions of nicotine, and soapy solutions were of small value 

 for the destruction of the eggs. Ova deposited on the twigs after the 

 wood was thoroughly sprayed with the lime-sulphur solution hatched, 

 and the young nymphs were not harmed through contact with the 

 material on the bark of the trees. On the other hand the wash 

 having considerable amounts of sediment (15-20-50 formula) was 

 less destructive to the eggs but the young psyllas which hatched 

 for the most part failed to reach the opening buds and these suc- 

 cumbed to the action of the sediment which became attached to 

 their bodies after leaving the egg shells. 



The chief factors which make for efficient work against the hiber- 

 nating " flies " and their eggs are (1) a knowledge on the part of 

 the grower of the habits of the " flies " and an acquaintance with 

 the eggs; (2) an understanding of the conditions under which 

 these stages are most vulnerable to sprays; (3) thorough work in 

 spraying. 



