VEGETABLE AND FIELD CROPS 277 



cooking, provided they are consumed promptly or kept in 

 cold storage. 



This wilt is closelj' related to the watermelon and cotton 

 wilt. Soils which have once borne a sick crop are infected 

 and will infect future crops. The general means by which 

 a field may become infected have been discussed on page 65. 

 In addition to these means of infection, the potato wilt is 

 often carried to new fields by infected " seed." 



For this reason all seed introduced from other fields 

 should be carefully inspected to guard against such infection. 

 It is a matter of record that this disease was largely intro- 

 duced into California from Oregon by means of infected 

 tubers. A little care a few years ago would have accom- 

 plished what seems now to be impossible, the prevention of 

 the disease in that region. Residents of other regions still 

 uninfected should profit by this example and exercise such 

 precaution as to avoid a similar fate. The disease may pass 

 to the manure by feeding infected potatoes to stock, and 

 this manure may lead to the infection of new fields. 



Cro]) rotation will partially restore infected fields to health. 

 Collecting and burning of the tops after digging will diminish 

 the amount of the fungus and add to the benefit of rotation. 



If diseased potatoes must be stored for any length of time, 

 all that are badly <lisca.sed should be rejected, and the re- 

 mainder kept as cool as possil)le without freezing them. It 

 is best to sell or consume su<;h tubers at once. 



Wilt, bacillose {Bacillus fsokmacearum E. F. Smith). — 

 This wilt, chiefly jirevalent from Maryland southward, 

 reportt'fl also from Indiana, Nebraska, and Iowa, is identi- 

 cal with that of eggplant, tobacco, and tomato, and is to a 

 large (>xt('iit transmitted to tiie plants i)y insects. 



