Root-knot Nematode or Gallworm 



METHODS OF CONTROL 

 Prevent Spread of Nematodes 



In order to prevent the spread of this pest, the same precautions 

 should be observed as in the case of the sugar beet nematode (See page 62) . 



Potatoes grown on infested land should not be used for seed, as the 

 nematodes pass the winter within the tubers. 



Such plants as tomatoes, cabbage, strawberries, kale, sweet potatoes, 

 asparagus and horse-radish should not be taken from infested soil and 

 transplanted in nematode free fields. 



Nematode Eradication 



There is no practical means of entirely eradicating the gallworm in 

 large fields. In the case of hotbeds and greenhouses soil fumigants can 

 be used, but these are too expensive for field use. 



Rotation 



The most practical method of reducing the numbers of nematodes 

 is to rotate with such crops as are not attacked. Mr. C. S. Scofield* 

 gives the following list of crops as suited for planting on infested soil : 



Barley Sorghum 



Oats Milo 



Wheat Kafir 



Rye Timothy 



Corn Red Top 



The value of growing the resistant crops named above is strikingly 

 illustrated by the results of a survey of five large areas in which all sugar 

 beet fields infested with the root-knot nematode were located and a record 

 secured of the crop grown on all fields, both infested and uninfested the 

 year previous. It was found as the per cent of resistant crops grown 

 increased, the per cent of infested beet fields decreased. These figures 

 are given in the following table: 



% of total 



Total fields % of total growing nematode 

 Area examined infested resistant crops 



A 366 58.47 5.19 



B 480 51.87 6.66 



C 768 28.77 9.77 



D 671 2.08 12.09 



E 676 1.03 28.06 



LIFE HISTORY 



During the greater part of their lives these worms remain embedded 

 within the tissue of the roots of their host plants. 



Upon reaching maturity the fertilized females begin the production 

 of eggs. Some of these hatch within the body of the parent, the young 

 ultimately escaping into the surrounding tissue of the host plant. Others 

 are laid at the rate of ten or fifteen daily.* 



*"The Nematode Gallworm on Potatoes and Other Crop Plants in Nevada." Circular No. 91, Bureau 

 of Plant Industry. U. S. Department of Agriculture (1912). 



65 



