ANNUAL REPORT, 1937 43 



250 gallons an acre, killed nearly all the beetles. This poison should be applied 

 before the middle of August so that it will not remain in too great quantity as a 

 residue on the berries when they are picked. 



One grower treated a bad infestation of this insect on August 30, using 6 pounds 

 of lead arsenate in 100 gallons of water and applying 250 gallons to the acre. 

 Some heavy rains fell on the treated area during September, two of them lasting 

 all cay. The berries were picked Oct. 2 and many of them showed spray residue 

 then. What seemed to be a sample with about the maximum amount of residue 

 was analyzed by the Fertilizer and Feed Control Division of the station at Amherst 

 with the following results: 



.0255 grains of lead per pound of fruit 



.01606 grains of arsenic trioxide per pound of fruit 



A similar sample analyzed by Arthur D. Little, Inc., showed .006 grains of 

 arsenic trioxide per pound. Another sample, left unpicked until the bog had been 

 flooded for five days after the general picking was done, was found by Arthur 

 D. Little, Inc., to show only .001 grains of arsenic trioxide per pound. It seems 

 from this that several days flooding will do much to remove an arsenical residue 

 from cranberries. 



As the experiment station analj-sis showed both lead and arsenic residue sub- 

 stantially above legal tolerance, special apparatus was devised and 700 barrels 

 of Howes berries were washed with a 2 percent solution of hydrochloric acid and 

 then thoroughly rinsed. They were then dried at the drying plant of the A. D. 

 Makepeace Co. and stored in a screenhouse from two weeks to a month. They 

 kept well and were finally marketed successfully as fresh fruit. 



Cranberry Fruitworm (Mineola). A spray of 8 pounds of derris powder (4 

 percent rotenone) and 2 pounds of soap in 100 gallons of water, applied at the 

 rate of 400 gallons an acre on July 10 and again on July 20, controlled this pest 

 almost completely on a bog where the worms took 40 percent of the crop on 

 untreated check areas. 



Ten pounds of cube powder (4 percent rotenone) and 2 pounds of soap in 

 100 gallons of water, applied at the rate of 400 gallons an acre, also gave good 

 control. 



Goulac, Ultrawet, calcium caseinate, SS-3, Ortho liquid spreader, coconut-oil 

 soap, and resin fish-oil soap were tried as spreaders for the derris and cube sprays, 

 the soaps giving the best results. 



It seems that with either derris or cube powder, two sprays are advisable for 

 control of the fruitworm, one to be applied when all but about a quarter of the 

 bloom is past and the other about ten days later. Small sample lots of the berries 

 should be examined before a bog is sprayed to determine the abundance and 

 condition of the fruitworm eggs present. 



Impregnated Pyrethrum Dust. The pyrethrum dust generally used by cranberry 

 growers is the flower heads of the pj-rethrum plant ground fine. It is thought that 

 only the pyrethrins on the surfaces of the particles of this dust are effective against 

 insects and that much more of these toxic principles is locked up in the interior 

 of the particles where they cannot function. Pursuant to this reasoning, some 

 manufacturers have prepared so-called impregnated or activated pyrethrum 

 dusts in which the pyrethrins are placed on or brought to the surface of the 

 particles. These dusts contain a considerably smaller percentage of pyrethrins 

 than is present in high-grade pyrethrum dust obtained by grinding the flower 

 heads, and so can be sold for less. Considerable attention was given to testing 

 these dusts in comparison with high-grade pyrethrum dust as controls for gypsy 

 moth caterpillars and blunt-nosed leafhoppers (Ophiola). As a general result of 



