340 DISEASES OF ECONOMIC PLANTS 



art^ as prevalent in nearly all parts of Long Island upon 

 many different varieties of sweet corn. In some cases the 

 entire crop was ruined, and 20 to 40 per cent of loss was 

 frequent, though in the majority of cases the loss was so 

 slight as to pass without notice. 



The diseased plants wilt and dry up much as though for 

 want of water, yet in soil that is amply water supplied. 

 While the wilting is most liable to occur at flowering time, 

 it may appear at any stage of growth when the plants are 

 25 cm. or more in height. In mild cases the lower leaves 

 wilt first, while in severe cases all wilt at one time. The 

 death of the plant may come in four days after the first 

 signs of disease show, or may be delayed a month, possibly 

 with recovery and relapse intervening. 



The roots remain normal, but the veins in the stems 

 appear as yellow streaks, in older cases black, instead of 

 their normal color. Such stems, if cut crosswise, shortly 

 exude a yellow, viscid drop at the ends of the veins. This 

 is the most distinctive character, and infallibly indicates 

 the presence of the wilt. Death is caused by the plugging 

 of the water passages with this viscid substance, which con- 

 sists mainly of bacteria. 



In the fields the diseased plants are scattered unevenly, 

 young and old stages and healthy plants together, health 

 and disease even in the same hill ; yet there appears to be no 

 direct plant-to-plant infection, nor any of that centrifugal 

 spreading from a diseased center that is so noticeable in 

 most wilt or soil diseases. 



The causal organism is found in the seed from affected 



1 Stewart, F. C, N.Y. (Geneva) Agr. Exp. Sta. Bui. 130, December, 

 1897. 



