New York Agricultural Experiment Station. 359 



spraying just as the blossoms drop. The most satisfactory spray 

 is Black Leaf 40, using three-fourths of a pint to one hundred gallons 

 of water to which are added from three to five pounds of dissolved 

 soap. (Formula 1.) 



4. Late summer spraying. — The grower should endeavor to combat 

 the pest by the preceding measures and thus avoid, if possible, the 

 necessity of later spraying. If the trees are badly infested during 

 the summer time it is a very difficult task to bring the pest under 

 control as there is an intermingling of all stages of the insect, and 

 some of them are resistant to any spraying mixtures which can 

 safely be used on foliage. Moreover the leaves, especially if the 

 growth is heavy, seriously interfere with thorough treatment, and 

 there is also danger that foliage injured by the psylla may be 

 further damaged by the applications of the sprays. 



Frequent and thorough spraying with the nicotine extract (For- 

 mula 1), on the first discovery of injurious numbers of the insects 

 is the most satisfactory means of affording protection to the trees. 



NUMBER OF SPRAYINGS NECESSARY TO CONTROL THE PSYLLA. 



With careful work it is not necessary to carry out all of these 

 measures each year. If the trees have been carefully scraped a 

 combination of treatments (1) and (2) or (1) and (3), as explained 

 above should be sufficient. Some growers have entirely controlled 

 the psylla with treatment (1) alone to kill the hibernating 

 flies. 



SPRAYING MIXTURES AND FORMULAS. 

 Formula 1. Nicotine Extract. 



Nicotine extract 40 per ct. (Black Leaf 40) f pt. 



Water 100 gals. 



Soap 3 to 5 lbs. 



This is recommended for winter spraying to destroy the flies or 

 for summer treatments to kill the young nymphs. 



Formula 2. Lime-Sulphur Mixture. 



Lime-sulphur solution (32°-34° B.) 1 ga l. 



Water 8 to 9 gals. 



To be applied just as the blossom cluster-buds separate at the tips 

 to destroy psylla eggs about to hatch and newly-emerged nymphs. 



Formula 3. Kerosene Emulsion. 



Kerosene 2 gals. 



Whale-oil or fish-oil soap \ lb. 



Soft water 1 g a l. 



Directions for making kerosene emulsion are as follows: 

 Dissolve the soap, which has been finely divided, in one gallon of 

 boiling water. Remove the vessel from the stove and add the oil. 



