III.— EXPERIMENTS IN CONTROLLING THE TOMATO 

 FRUITWORM WITH ARSENICALS. 



By Thos. H. Jones, 

 Entomological Assistant, Truck-Crop Insect Investigations. 



Spraying and dusting experiments for the control of the tomato 

 fruitworm (Chloridea ohsoleta Fabricius) were conducted during 

 1916 and 1917 at the Louisiana Experiment Station, Baton Rouge, 

 La. This work was carried on in cooperation with Dr. C. W. Edger- 

 ton, plant pathologist of the station, who was especially interested 

 in the fungicidal value of some of the materials used. 



In 1916 a spring and a fall crop of tomatoes were used in the ex- 

 periments. In the case of the fall crop a heavy frost occurred be- 

 fore much fruit had matured. The next day all fruit was gathered 

 and weighings and counts made. In 1917 only a spring crop was 

 used in the experiments. 



The sprays were applied by means of small compressed-air spray- 

 ers of about 2J gallons capacity. The materials were carefully ap- 

 plied. On the spring crop of 1916 about 10 gallons of spray were 

 used on an average in spraying eight times a row of 54 plants, set 

 2 feet apart in the row. On the fall crop of 1916 approximately 4§ 

 gallons were used in spraying the same number of plants seven 

 times. For spraying the same number of plants five times in the 

 spring of 1917 about 7 gallons were used. 



The dusting was done with a dust gun. In dusting the spring 

 crop of 1916 approximately 17 ounces of undiluted powdered ar- 

 senate of lead were used in making eight applications to an aver- 

 age row of 54 plants, set 2 feet apart in the rows. In dusting the 

 same number of plants of the spring crop of 1917 five times, ap- 

 proximately 12^ ounces were used. For the dusting a specially 

 prepared, light, finely powdered arsenate of lead was used, as was 

 also used in spraying the spring crop of 1916. 



In Tables I-III " wormy " refers to fruit that was apparently 

 injured by the larva of Chloridea ohsoleta. Without doubt the in- 

 jury to a small percentage of this fruit was due to other causes, 

 principally the hornworms, P hie gethon tins spp. and larvse of the 

 granulated cutworm* Feltia annexa Treitschke. 



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