February, '19] SANDERS: potato wart disease 89 



"eye," and there rapidly develops a ver>' distinct, wartj^ growth, usu- 

 ally brownish in color. These warty growths enlarge rapidly, and 

 ultimately cover and transform the entire potato to a warty mass, 

 somewhat resembhng a piece of cauliflower head. This stage having 

 been reached, the warty mass decays in the ground, thereby releasing 

 myriads of thick, heavy walled spores, which remain viable in the soil, 

 according to experiments carried on in Europe, for more than six years 

 — even in the absence of potato growth. In other words, the disease 

 has appeared after a six-year rotation of crops other than potatoes, and 

 has attacked potatoes planted the following season. No definite 

 records are available regarding the exact longevity of the spores in 

 the soil, though it is highly probable that a ten-year period must 

 elapse before infected soil can be considered absolutely safe for potato 

 planting. 



The disease can be transferred to clean soil in several ways, most 

 important of which are through infected seed potatoes, infected par- 

 ings, spring freshets carrying infected soil to new localities, the removal 

 and transfer of root crops from infected gardens to new localities, and 

 still another very important and unsuspected method is that of its 

 possible transmission by manure from animals, which have been fed 

 on uncooked potatoes infected with this disease. It will be seen, 

 therefore, that the control measures which must necessarily be adopted 

 in dealing with this pest are somewhat varied, and will require no in- 

 considerable attention to details, combined with the necessaiy legal 

 power and authority. 



It is proposed to quarantine the entire affected area, including the 

 few outlying infections, from which quarantined area we will prohibit 

 the removal of potatoes, root crops, manure and any materials which 

 might carry the disease. Within the quarantined area certain "re- 

 stricted" areas will be designated, within which the growing of potatoes 

 will be prohibited. In order to further supervise the inspection for the 

 disease in future years, it seems desirable to permit the growing of 

 potatoes within the quarantined area only by license furnished from 

 the Pennsylvania Department of Agriculture. 



It is now contemplated that a laboratory for the more careful study 

 of this disease will be established — probably at Freeland — and in addi- 

 tion to studies of the rapidity of dissemination, the life-history and 

 etiology of the disease, certain experiments will be carried on, using 

 steam sterilizing methods in an effort to kill the spores in the soil. This 

 treatment, if successful, will be particularly valuable, even though 

 somewhat expensive, in outlying infections where only small areas need 

 treatment. 



I wish to express my sincere thanks and appreciation for the assist- 



