TOBACCO DISEASES AND THEIR CONTROL. 



17 



Control. — Where Fusarium wilt threatens to become serious, 

 growers are advised not to grow tobacco on the infested soil for at 

 least three years. So far as definitely known, this particular para- 

 site does not attack any other plants. It is so similar, however, to 

 the potato Fusarium wilt that, as a matter of general precaution, 

 it is not advisable to grow potatoes in rotation with tobacco on 



Fig. 11. — A tobacco plant stunted by black root-rot. A healthy root system is shown 



at the right. 



infested soils. Precautions should also be taken to prevent the 

 spread of the disease to uninf ested fields through the use of infected 

 plants for transplanting or the transfer of soil. A hopeful means 

 of control, should conditions warrant it, lies in the development of 

 disease-resistant strains within the various susceptible varieties. 



91061°— 24 2 



