THE SO-CALLED TOBACCO WIRE WORM IN VIRGINIA. 25 



there was scarcely any plantain (Plantago lanceolata) after a heavy 

 application of lime had been made, and there was an excellent crop 

 of alfalfa. In the unlimed check plats plantain nearly covered the 

 ground, and there was a very poor growth of alfalfa. 



Increased fertility of the soil may also aid in the extermination of a 

 weed, as was noticed where heavy applications of acid phosphate had 

 been made to meadow land on which there was a heavy growth of 

 the oxeye daisy. The year following the application of the acid 

 phosphate but few plants of the daisy could be seen. In this manner 

 certain weeds may often be crowded out by grasses or clovers which 

 are enabled to make better growth owing to greater fertility. 



The experience of the best tobacco growers has shown that intensive 

 culture gives largest profits, and no expense or trouble should be 

 spared in putting the ground in the best possible condition in every 

 respect before the crop is planted. By commencing the preparation 

 of weedy land the year before it comes in corn or tobacco, an excellent 

 opportunity is afforded to apply lime. Such land can often be con- 

 veniently plowed in winter and during spring or early summer, and 

 easily be put in condition for such crops as crimson clover, cowpeas, 

 etc., which may be profitably followed by tobacco or corn the succeed- 

 ing year. 



FERTILIZERS. 



From observations of tobacco fields during the seasons of 1910 

 and 1911 it is evident that where the land receives heavy applications 

 of nitrogenous fertilizers the damage from the worms is not so great 

 as where light applications are made. Just as many plants are 

 attacked by the worms, but vigorous and rapidly growing plants 

 are more apt to recover from injury. This was very noticeable in the 

 fertilizer test plats of the Virginia experiment station at Appomattox 

 in 1910. 



INSECTICIDES AND REPELLENTS. 



The following insecticides and repellents were tested: Arsenate of 

 lead, Paris green, tobacco extract, nicotine sulphate, tobacco dust, 

 kerosene, kainit, and calcium cyanamid. In no instance were results 

 secured which would indicate that the substances tested were of much 

 practical value in combating the tobacco Crambus. The following 

 field notes give details of some of the experiments : 



ARSENATE OF LEAD. 



In experiment A, with powdered arsenate of lead, 1^ ounces of the poison to 2 \ 

 gallons of water was used. Two hundred plants were treated, the entire plant being 

 dipped into the solution. The plants were set in land which had been prepared a 

 few days before. The field had been weedy and the worms were numerous. Two 

 hundred untreated plants were kept as a check. On examining the plants five days 

 later 22 injured plants were found in the poisoned plat and 36 injured plants in the 



