48 Diseases of Truck Crops 



very characteristic (fig. 7 c, d). Some Fusaria also 

 produce chlamydospores or resting spores, by which 

 the fungus is carried over winter (fig. 7 e). As far as 

 we know the wilt-producing Fusaria do not form a 

 winter or ascus stage. They are carried over as 

 mycelium, or chlamydospores, in dead plants and in 

 the soil. 



2. Soils Rendered Sick by Certain Forms 

 of Animal Life 



The present discussion deals with the root knot, a 

 disease produced by a little worm generally known as 

 nematode, or eel worm. 



Root Knot 



Caused by Heterodera radicicola (Greef) Mull. 



Root knot is most prevalent in light soils. This, 

 however, does not exclude it from heavier lands where 

 it may sometimes be found. The trouble is most 

 widespread in the Southern States, where the winter 

 is mild. In unprotected places in the North its 

 numbers are probably greatly reduced each winter. 

 The annual financial losses from this disease are 

 staggering in extent. With proper culture and fer- 

 tilization, however, a crop may be produced with 

 practically very little loss where neglect would have 

 caused a total failure. This is especially true under 

 greenhouse conditions. 



