April, '15] 



^IcCOLLOCH: DUST FOR CORN-EAR WORM 



213 



with different strengths of Corona dry arsenate of lead. The silks 

 in Plot 1 were dusted with 100 per cent arsenate of lead, those in Plot 

 2 with 63 per cent arsenate of lead, and those in Plot 3 with 50 per cent 

 arsenate of lead. Sulphur was used as a carrier of the lead in Plots 

 2 and 3. A fourth plot was kept for a check. The dust which was 

 applied by shaking from an ordinary cheese-cloth bag was applied 

 every, three days during the time the silks were fresh. No attempt 

 was made to get the poison on any other part of the plant. Owing to 

 the dry weather the applications were made more frequently than 

 would ordinarily be necessary. The results of this experiment are 

 shown in the table. 



Table Showing the Results of Dusting Corn to Cot^tbol Ear-Worm Injury 



Plot 



Treatment 



Cost 



Per Cent Ears 



Per Cent Grain 



Amount 

 Mould 

 Injury 



Yield 



Poison 



Labor 



Total 



Injured 



Injury 



1. . . . 



100% A. of L. 



S3. 36 



SI. 76 



So. 12 



63 



Less than 1% 



None 



10.7 bu. 



2.... 



63% A. of L. 



1.82 



1.61 



3.43 



66 



Less than 1 % 



None 



12.6 " 



3.... 



50% A. of L. 



2.20 



1.70 



3.90 



88 



About 5% 



Moderate 



12.5 " 



4. . . . 



Check 









98 



About 10% ' 



Bad 



11.9 " 



While over 60 per cent of the ears in Plots 1 and 2 were injured by 

 worms the damage was so slight as to be almost negligible. In almost 

 ever}^ case only one or two grains were injured on each ear and the 

 usual moulds and fungi which accompany corn-ear worm work were 

 not present. In the check plot the injury due to the ear-worm and to 

 the accompanying moulds and fungi was so bad that much of the corn 

 was unfit for feeding to stock, especially to horses. 



The results of the past summer show that the 63/ per cent mixture 

 controlled the corn-ear worm practically as well as did the pure arsen- 

 ate of lead. The difference in cost, however, was about $5.00 less per 

 acre in favor of the 63 per cent arsenate of lead. 



From the results given in the table it is seen that the cost of this 

 treatment is prohibitive where corn is grown for forage and grain 

 purposes. It is the opinion of the author that this cost can be reduced 

 fully one-half by lengthening the period between applications to five 

 days and by using a cheaper carrier, such as hydrated lime. This, 

 however, would still make the cost at least $5.00 per acre. Where 

 corn is raised for show purposes or for seed and roasting ears, dusting 

 can be recommended as being very profitable. Sweet corn can be 

 sold on the market for from five to ten cents more per dozen ears, 

 when it is known to be free from ear-worm injury. 



