CONTROL OF TOBACCO WILT IN THE FLUE-CURED DISTRICT. 17 



although the loss would be greatly reduced, as shown by the results 

 for 1914. 



After the disease has been brought under control, it is thought 

 that a good crop of tobacco can be grown every fourth or fifth year. 

 Under no circumstances should a crop of tobacco be followed directly 

 by a second one. Farmers are strongly advised against doing this, 

 no matter how effectively the wilt may have been brought under con- 

 trol, for by this procedure the beneficial effects of the rotation will 

 be largely undone and a correspondingly longer period of rotation 

 will be required to restore the soil. 



PRECAUTIONS TO PREVENT THE SPREAD OF THE DISEASE. 



Although the rotation of crops makes it possible to grow tobacco on 

 land infested with wilt, those farms in the wilt area that are still 

 free from the disease command a considerable premium, because a 

 larger acreage of tobacco can be grown on them. It is clearly to the 

 interest of the owner to use every possible means of keeping his farm 

 free from the tobacco wilt. Thorough burning of tobacco seed beds 

 will destroy the wilt parasite, but the seed bed may become reinfested 

 if diseased soil from surrounding fields, even in very small quanti- 

 ties, is allowed to reach the bed after it has been sterilized. The seed 

 bed, as well as the field, also may become infested by surface drainage 

 from infested fields. This explains the frequent observation by 

 farmers that wilt may appear in the first crop of tobacco grown on 

 freshly cleared lands, a fact which should serve as a warning of 

 what may be expected if the surface drainage from neighboring 

 wilt-infested farms is allowed to reach noninfested tobacco lands. 

 For the above reasons tobacco growers are advised to avoid setting 

 in fields free from infestation plants obtained from seed beds which 

 may be infested. A half dozen infected plants may easily be the 

 means of establishing the wilt permanently on a plantation. 



There is no reason for supposing that the disease is carried over 

 in the seed, and there is no doubt that the two principal sources 

 from which healthy fields receive the disease are (1) soil from 

 infested fields and (2) diseased tobacco plants, either living plants 

 or the dead material of leaf, stem, stalk, or root. Infested soil car- 

 ried on a plow borrowed from a neighbor or on the feet of an animal 

 or of a man may serve to introduce the disease. In the process of 

 flue curing it might be expected that the comparatively high tem- 

 peratures used toward the end of the curing would be sufficient to 

 kill the parasitic organism, but cases have been observed in Gran- 

 ville County in which it is highly probable that the wilt was intro- 

 duced on tobacco farms through the use of stems as a fertilizer. It 

 is not advisable to use tobacco stalks or stems from diseased fields on 

 lands not already infested with wilt, since the curing process can not 



