340 MANUAL OF VEGETABLE-GARDEN INSECTS 



pearly white globules embedded in the tissue. Each female 

 is capable of producing about 500 eggs, which are laid at the 

 rate of ten or fifteen a day. The eggs form a mass often as 

 large as the female and are surrounded by a gelatinous sub- 

 stance. The eggs are ellipsoidal or sometimes kidney-shaped, 

 about twice as long as broad and vary greatly in size, being 

 from about s^t? to ^io inch in length. Sometimes the eggs 

 hatch while still within the body of the mother. The female 

 begins to lay eggs about twenty-five days after entering the 

 root. The winter is passed in the larval stage in the galls and 

 in the surrounding soil. 



The galls produced on different species of plants are variable 

 in size and shape, but as a rule the amount of enlargement 

 depends on the number of worms entering a root near the same 

 point. Plants growing in light sandy soil are more subject 

 to injury than when on heavy land. The worms cannot sur- 

 ^'ive a thorough drying of the soil as is the case with many 

 related forms and are killed if the soil remains saturated with 

 water for a long time. 



Means of control. 



Vegetables susceptible to the root-knot disease should not 

 be planted on land known to be infested. To free fields of the 

 root-knot nematode, they should be planted for one or two 

 years to some crop not susceptible to the disease and which 

 has a sufficiently rank growth to crowd out all weeds that might 

 harbor the pest. Certain varieties of cowpeas, particularly 

 the Iron, are not susceptible and are sometimes used for this 

 purpose. After the cowpeas are harvested, the ground should 

 be plowed and sowed to some winter grain such as rye or wheat. 

 The next season another crop of cowpeas should be sown to 

 be followed again by grain the second winter. Under certain 

 conditions velvet beans or Florida beggarweed may be used 

 instead of cow^peas. Care should be taken not to allow weeds 



