116 



VEGETABLE FORCING 



convenient forms for greenhouse sprayers. Hand 

 atomizers are very useful for treating small lots of plants. 

 An extensive Ohio grower uses a pressure tank mounted 

 on a cart. A very long half-inch hose enables him to 

 spray the houses with only an occasional moving of the 

 cart. The plan is entirely satisfactory. 



Nematodes (Heterodera radicicola). These little 

 pests, which are nearly microscopic in size, are variously 

 known as gall worms, eelworms and thread worms. The 

 trouble which they cause is often referred to as root knot 

 and root gall, and sometimes as big root. The last term 

 should not be confused with the malady "big root" and 

 "club root" of cabbage and other brassica, caused by a 

 slime mold. Nematodes are widely distributed through- 

 out the temperate and tropical parts of the world. High 

 temperatures and long summer seasons are most favor- 

 able for their existence, and for these reasons they arc 

 most troublesome in southern sections. 



Greenhouse conditions are naturally ideal for nema- 



todes. They are es- 

 pecially destructive to 

 the cucumber and to- 

 mato, and they some- 

 times infest asparagus, 

 muskmelon, pea, bean, 

 beet, celery, carrot, 

 eggplant, pepper, on- 

 ion, spinach and radish. 

 More than 500 kinds of 

 plants are said to be 

 subject to the attack of 

 nematodes. Roots with 

 soft, tender tissues, 

 such as the cucumber, 



Fig. 38. Roots of tomato plant completely provide favorable COn- 



8a " worms ' (After Ge rge F ' ditions for this enemy. 



