THE SO-CALLED TOBACCO WIREWORM IN VIRGINIA. 23 



inches. The tobacco in all plats was planted at the same time. The 

 kind and amount of fertilizer applied was the same in all plats, and 

 after the first cultivation all plats received the same treatment. The 

 land was divided into 3 plats of 2 acres each and 1 plat containing 

 one-half acre. Below are given the details of each experiment and 

 the results obtained. 



Plat No. 1 contained 2 acres. It was deeply plowed and subsoiled 

 in February, 1911 . The land was thoroughly disked and harrowed at 

 frequent intervals during March, April, and May and kept almost 

 entirely free from weed growth until tobacco was planted. The stand 

 of tobacco was practically perfect. Only an occasional plat could be 

 found which showed damage from Crambus larvae. 



Plat No. 2 contained 2 acres. The land was deeply plowed and 

 subsoiled in February, 1911, and was not disturbed until prepared for 

 planting in May, when it was deeply disked, harrowed, and bedded 

 just before planting. Ninety-four per cent of a stand was secured at 

 the first planting. The plat was reset once. 



Plat No. 3 contained one-half acre. The land was plowed and sub- 

 soiled in February, 1911, as in plats Nos. 1 and 2. The land was not 

 disturbed until prepared for planting as in plat No. 2. Weeds and 

 grass were allowed to grow after planting. The middle of the row 

 was not disturbed until after the first cultivation, in order to provide 

 natural food for the Crambus larvae, so that they would not be forced 

 to attack the tobacco plants. The infestation of this plat was not 

 heavy enough, so that the effect of tins treatment, which is said to be 

 practicable under certain conditions, could be accurately determined. 

 The stand of tobacco secured at the first planting was 96 per cent. A 

 few larvae were found in the weeds left in the middle of the row. 



Plat No. 4 was used as a check. The land was plowed and pre- 

 pared for planting just before the tobacco was set out. The w^eed 

 growth and general conditions were similar to those in plats Nos. 1, 

 2, and 3. The stand secured at first planting was 86 per cent. The 

 tobacco was replanted twice. In land adjoining this tract which had 

 been under clean cultivation during the previous summer and where 

 there was no weed growth, about 98 per cent of a stand of tobacco 

 was secured at the first planting. This land had been prepared for 

 planting in practically the same manner as in the check plat, No. 4. 



CHEMICAL SPRAYS FOR WEED DESTRUCTION. 



Certain chemical sprays, such as iron-sulphate (copperas) solution, 

 copper-sulphate (bluestone) solution, and common-salt solution, are 

 frequently used for eradicating weeds and under certain conditions 

 have been found very effective. The success of this method of erad- 

 icating such weeds as oxeye daisy and wild mustard from grain and 

 pasture fields without injury to the grains or grasses depends largely 



