298 Diseases of Truck Crops 



minute warts consisting of whitish to yellowish fun- 

 gus threads. Very often in pulling out a plant 

 which is partly infected, the young healthy rootlets 

 or even those which are partly destroyed are found 

 to be colored pinkish buff. 



The Organism. The organism which causes Texas 

 root rot is, as far as we know, sterile. By this is 

 meant that the fungus reproduces by division 

 and further growth of its mycelium, but produces 

 no fruit (fig. 28 q and r). Duggar 1 claims that the 

 pink buff color mentioned above represents the 

 colored spore masses of the fungus which he named 

 Phymatotrichum omnivorum (Shear) Dug. However 

 no inoculation experiments have been carried out to 

 prove that this fruiting stage is in any way connected 

 with Ozonium. In establishing the relationship of 

 various stages of apparently the same parasitic fun- 

 gus, inoculation experiments alone should be the 

 crucial test. 



Control. No definite methods of control are as 

 yet known. Deep plowing undoubtedly retards the 

 work of the disease, but it does not prevent it by any 

 means. Crop rotation should be resorted to. In the 

 system of rotation may be included sweet corn, cab- 

 bage, radish, spinach, kale, mustard, lettuce, and 

 cauliflower. Crops to be omitted from the rotation 

 are beans, beets, cowpeas, sweet potatoes, eggplants, 

 tomatoes, and peppers. The latter two are only 

 partly susceptible to Texas root rot. 



ROOT KNOT (fig. 54 b), see NEMATODE, p. 49. 



1 Duggar, B. M., Ann. Missouri Bot. Gard., 3: 11-23, 1916. 



