8 Department Circular 329, U. S. Dept. of Agriculture 



for controlling this disease. Despite publicity given to cotton wilt and methods 

 of control used in previous years, many farmers with infested fields are un- 

 familiar with the disease and the preventive measures necessary for its con- 

 trol. Demonstrations were held in Edgecombe, Lenoir, and Richmond Counties. 

 which illustrated the control of the wilt trouble through the use of Dixie- 

 Triumph wilt-resistant cotton. The yield from wilt-resistant cotton on 1-acre 

 demonstration plots averaged approximately twice that of susceptible cotton 

 on adjoining plots. These demonstrations have convinced the growers of the 

 advisability of planting this cotton on infested areas, and as a result more 

 extensive plantings of this variety will be made in 1924. 



Generally, in territory where disease-resistant strains of plants 

 could be used to advantage, it was not difficult to induce farmers to 

 grow them. In such localities the work, for the most part, has passed 

 beyond the demonstration stage and the problem is to establish a 

 source of seed supply of a type to meet the local market require- 

 ments. This was accomplished through maintenance by the Depart- 

 ment of Agriculture of a pure-seed stock of certain resistant varieties 

 of tomatoes and asparagus, and in the case of cabbage by the De- 

 partment of Agriculture and the University of Wisconsin. The de- 

 partments of plant pathology in xmie States have developed strains 

 of resistant plants which meet local requirements. This pure-seed 

 stock was usually made available by the Government and States to 

 reliable seedsmen for multiplication. 



According to J. C. Walker, plant pathologist of the Bureau of 

 Plant Industry, during 1922 and 1923, 3,200 pounds of wilt-resistant 

 Wisconsin All Seasons cabbage seed were grown under supervision 

 by the National Kraut-Packers' Association, and distributed to its 

 members and to farmers outside of the association. The production 

 of this seed stock was closely supervised by the Department of Agri- 

 culture, with the result that a check was kept on the degree of resist- 

 ance of the plants. 



Of the 1921 seed catalogues, more than 100 listed rust-resistant 

 varieties of asparagus; more than 15. wilt-resistant cabbage; and 

 more than 25. the wilt-resistant tomatoes developed by the depart- 

 ment. An effort was made to keep county agents informed as to 

 these sources of supply in order that they might furnish the informa- 

 tion to farmers on request. 



SEED DISINFECTION 



The number of diseases known to be carried on or within the seed 

 of plants is constantly being increased. Since many of our economic 

 plants fall in this group, projects on seed disinfection played an 

 important part in the extension program. Xo attempt is made to 

 cover the entire subject in this circular. Instead, reference is made 

 only to a few activities which illustrate particular features of seed 

 disinfection. 



For some diseases, seed treatment combined with rotation to in- 

 sure planting on disease-free soil is the only practical control meas- 

 ure known. Other diseases, when not distributed in a growing sec- 

 tion, may be controlled by a cheap seed disinfection, making unneces- 

 sary the use of a spray which at best is only partially effective. 

 For certain other troubles, seed treatment is but one of several means 

 of control which are necessary to insure a satisfactory reduction of 

 loss. 



