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MASS. EXPERIMENT STATION BULLETIN No. 285 



Table 9. — Percentage of Harvested Fruit Injured by Plum Curculio. 

 Middlesex Countv, 1931 



USE OF DUST FOR CONTROL OF PLUM CURCULIO 



Laboratory experiments have shown that a dust containing 15 per cent of 

 lead arsenate has compared very favorably with liquid sprays of lead arsenate. 



In 1931, a block of trees in the orchard of Mr. George A. Drew, Westford, 

 Massachusetts, was dusted with 85-15 sulfur-lead arsenate dust, while another 

 block was sprayed with the recommended formula of lead arsenate 4 pounds, 

 lime-sulfur solution 1 1-3 gallons, hydrated lime 10 pounds, fish oil 1 pint, water 

 100 gallons. The special curculio application was made to each block on May 29, 

 and a second application was made on June 15. All apples from the June drop to 

 harvest on 12 trees were examined for curculio injury. Gravenstein was the main 

 variety in each block. The fillers in the sprayed block were Astrachan, and in the 

 dusted block. Wealthy. More than 42,000 apples were examined, and the per- 

 centage of all fruit injured by curculio was 5.74 in the sprayed block and 6. 12 in the 

 dusted block. The difference between the treatments was also less than 1 per cent 

 in the harvest fruit of all varieties, as well as in the Gravenstein harvest fruit. 

 This seems to indicate that under conditions which prevailed in 1931 dusting 

 was practically as effective as spraying, and gave satisfactory control when 

 applied in this orchard. A summary of these records is given in Table 10. 



Table 10. — Comparison of Spraying and Dusting for Control of the Plum 

 Curculio in Apples. Westford, Mass., 1931 



