New York Agricultural Experiment Station. 403 



plant will completely recover, or it may recover for a time and 

 succumb to the disease later. Occasionally, all of the leaves of a 

 plant will wilt simultaneously (this is most likely to happen with 

 small plants), but more often they die one after another so that 

 wholly dry leaves and green leaves may be seen on the same 

 plant. There is no abnormal coloration — it is simply a drying 

 up of the tissues. There is nothing abnormal about the roots and 

 the subterranean portion of the stem appears sound and normal 

 except in the case of plants which have been dead for some time. 

 Such plants may show black decay spots on the subterranean 

 stem; but decay does not set in until the whole plant is dead and 

 even then progresses slowly. The fact that the whole interior of 

 the lower end of the stem is brown signifies nothing. This 

 browning is found in healthy plants as well as in the diseased 

 ones. 



The most distinctive character of the disease is revealed when 

 the stem is cut lengthwise. The fibro-vascular bundles appear as 

 yellow streaks in the white parenchyma; but in the stems of 

 plants which have been dead for some time some of the bundles 

 may be black instead of yellow. If the stem is cut crosswise and 

 the cut surface exposed to the air for about five minutes, a yellow, 

 viscid substance exudes in drops from the ends of the vessels. 

 This yellow substance in the fibro-vascular bundles is composed 

 of bacteria. It is an invariable accompaniment of the disease and 

 in plants which have died from the disease it will be sufficiently 

 abundant to be seen easily with the naked eye. Thus we have 

 in this yellow substance a character by which the disease may be 

 readily identified. It should be stated, however, that in very 

 young plants the yellow substance is detected less easily than in 

 large ones with well-developed vascular systems; and, also, that 

 the microscope will show its presence in the vessels of the plants 

 before it can be detected with the naked eve and before there is 



t/ 



any outward manifestation of the disease except in the dwarfed 

 condition of the plants. 



Fields of sweet corn affected with the disease are verv uneven, 

 particularly at the time when the ears are forming. Plants in 



