240 INSECTS, DISEASES AND OTHER PESTS 



rotted ofF at the same time. Still another' generalization 

 can be made. The rotting of a plant with a single stem is 

 always general, that is, the disease after it is estabHshed 

 will extend from the roots to the branches, while in a dis- 

 eased plant which is forked below ground the rot is always 

 localized at the fork and seldom progresses into the main 

 stem toward the roots. Therefore, it would be more 

 advantageous to put in plants with a single stem which 

 break at least i in. to 2 in. above the surface of the soil. 



There is a well-known statement that setting the 

 plants too deeply will cause them to be much more sus- 

 ceptible to stem rot. It does not make so much difference 

 how deeply plants with a good, long, single stem are set, 

 so long as they break above ground. However, if plants 

 with a short stem, breaking low, are planted so that the 

 fork is below ground, the fungus has a much better chance 

 to attack the plants. The reason for this is obvious for 

 they can be much more easily injured in cultivating, and 

 the fungus does not encounter as thick a bark on the 

 branches as on the main stem. 



Usually the first indication of the disease is a paler 

 green color of the entire plant or of a single branch. The 

 plant does not wilt at once, for the lighter green color of the 

 foliage may be noticed for a week or so before the actual 

 wilting takes place. During cloudy weather the plant 

 may not wilt for two weeks, and sometimes even longer, 

 although the stem may be completely rotted. On sunny 

 days the plants wilt much faster. During the course of 

 our work on this disease, it appears that transpiration and 

 temperature play a great part in the length of life of the 

 plants after they are infected. 



If the stem of a plant that shows the first sign of 

 wilting is pressed just above the soil, a soft area is usually 



