THE SO-CALLED TOBACCO WIREWOKM IN VIRGINIA. 



21 



A). On plat No. 1 the effect of mowing and burning the weeds after 

 the eggs had hatched was noted. 



Plat No. 1. — Weeds mowed and burned during third week in September, 1909. 

 The land was not disturbed until the ground was prepared for planting, during the 

 third week in May. Number of plants in plat, 4,400. Number of plants reset, 610. 

 Per cent injured, 13.8 + . Tobacco replanted twice. 



Plat No. 2. — Ground plowed during last week in September, 1909. In March, 

 April, and May it was disked and harrowed at frequent intervals, no vegetation being 

 allowed to grow before the tobacco was planted, in order, if possible, to starve out the 

 hibernating larvae. Number of plants, 4,400. Number replanted, 415. Per cent 

 injured. 9.4+. 



Plat No. 3. — Land plowed during second week in March and not disturbed until 

 just before planting. Number of plants, 4,400. Number of plants reset, 410. Per 

 cent injured, 9.3+. 



Plat No. 4. — Land plowed during third week in December, 1909. Nothing further 

 done to it until prepared for planting during last week in May, 1910. Number of 

 plants, 4,400. Number replanted, 540. Per cent injured, 12.2+ . 



The results of these experiments are shown also in Table IX. 

 All plats were replanted twice. A good stand of 98 per cent was 

 secured by July 5. 



Table IX. — Effects of fall and winter treatment on injury by the tobacco Crambus 



in 1909 and 1910. 



Exper- 

 iment 

 No. 



Preliminary treat- 

 ment. 



Time of treatment. 



Later treatment. 



Time. 



Al 





Second week of December, 1909 



First week of January, 1910 



Thoroughly disked. 

 Disked 



First week of 



A2 



...do 



January, 

 1910. 

 Second week of 



A3 



..do 



Last week of February 



do 



February. 

 Third week of 



A4 



do 



Third week of March 



do 



March. 



A 5 



.do 







April. 



Bl 

 B2 



Weeds mowed and 

 burned. 



Third week of September, 1909 



Disked and har- 

 > rowed at fre- 

 quent intervals. 



Disked 



[March, April, 



B3 



..do 





( May. 



B4 



...do 



Third week of December 





B5 



do 



First week of April 









May. 



Exper- 

 iment 

 No. 



Planted tobacco. 



Number 

 of plants. 



Number 

 reset. 



Per cent 

 injury. 



Al 





2, 200 

 2,350 

 2,280 

 2,214 

 2,225 

 4,400 

 4,400 

 4,400 

 4,400 

 8,800 



89 

 165 

 138 

 251 

 375 

 610 

 415 

 410 

 540 

 1,218 



4 



A2 



do . 





A3 



do 



6 



A 4 



do 



11 



A5 



do 



17 



Bl 



Third week of May 



13.8 



B2 



do 



9.4 



B3 



do 



9.3 



B4 



do 



12.2 



B5 



do 



13.9 









In the season of 1910-11 another series of cultural experiments was 

 conducted on the J. F. Purdum farm, in Appomattox County, Va 

 The land previous to preparation for tobacco was in meadow 



