GRAPE PESTS 11 



but in some experiments the low pressure hand pump producing a greater volume 

 appeared slightly more effective. A power sprayer delivering 4 gallons or more 

 per minute at a pressure of 250 pounds or more would be very effective equipment. 

 The spra\'s were applied when the buds were starting to swell and about two 

 weeks before the larvae hatched. The actual date of application varied from 

 April 9 in 1942 to April 21 in 1939, depending on the early spring development. 

 The effectiveness of the treatment is expressed as the percentage of available 

 tips or new shoots (Fig. 5) which were infested with a larval web or nest. Counts 

 were made from May 19 to June 4 when the activity of the caterpillars was at 

 its height. If possible, at least 100 tips on each vine or trellis were selected at 

 random and examined. 



Table 7. — Dormant Sprays For The Control of The Grape Plume 

 Moth in Home Vineyards. 

 Waltham, Mass., 1939-1942 



Exper- Tips not Tips Infested Percent 



Material iments Infested Control' 



Number Number Number Percent 



None 11 390 885 69.41 



Liquid lime-sulfur 11% 3 224 241 51.8? 25.48 



Oil emulsion' 3% actual oil 



Alone 4 570 153 21.16 69.51 



Plus Nicotine sulfate 0.125% 1 81 19 19.00 72.62 



Plus DNOC2 15 oz. - 100 gal. 1 82 18 18.00 74.06 



Plus DNOCHPS 15 oz.-lOO gal. 1 86 14 14.00 79.83 



Sodium Dinitrc Cresylate* 



-}4% 3 942 234 19.89 71.34 



%% 1 100 9 8.25 88.11 



1 % 5 382 13 3.29 95.26 



1 14% 1 93 7 7.00 89.91 



hn 1939 Kleenup, Cal. Spray Chem. Co., was used; in 1940 and 1941 Spra-Cream, B. G. Pratt Co. 

 ^Dinitrc cresol powder supplied by Dow Chemical Co. 

 ^Dinitro phenol powder supplied by Dow Chemical Co. 

 ^Elgetol supplied by Standard Agr. Chem., Inc. 

 ^Abbott's formula (1). 



Discussion of Materials 



The natural infestation on unsprayed vines in the vicinity of Waltham is well 

 shown by the average of 69.41 percent for the four-year period. Although indi- 

 vidual counts ranged from 31.7 to 96.3 percent of the tips infested, the average 

 tip infestation for each year was: 1939—65.56, 1940—75.08, 1941—81.95, and 

 1942—55.46 percent. 



Lime-Sulfur. — In spite of promising results in laboratory tests, liquid lime- 

 sulfur diluted 1 part with 8 parts of water was not effective in field experiments. 

 In only one experiment was the infestation reduced significantly from that on 

 the untreated vines. This material was applied to a white painted arbor in one 

 test with disastrous effect on the paint. 



