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436 Other Management of the Vegetable-Garden 



the rate of 1 ounce (or sodium cyanide, % ounce) to 3,000 

 cubic feet of space contained in the house and the fumi- 

 gation should continue all night. Fumigate only on dark 

 dry nights when there is no wind. The house should be 

 as dry as practicable and the temperature not above 60 

 degrees F. Use with great care, as the material is very 

 poisonous. All forcing-house and hotbed plants should be 

 wholly free of white-fly when set in the field. 



Root-knot nematode or eel-worm {Heterodera radicicola). 



In the warmer parts of the country, many vegetable 

 crops suffer serious injury from minute worms that in- 

 fest the roots, causing swellings or nodules. They are very 

 troublesome in irrigated regions and in greenhouses. The 

 worms can persist in moist soil for a long time. They are 

 real worms, not the larvae of insects. 



To free fields of the root-knot nematode, rotate for two 

 or three years with a crop not susceptible to the disease 

 and that grows rank enough to keep out weeds that harbor 

 the pest. Immune varieties of cowpeas, such as the Iron, 

 followed by winter wheat or rye, are sometimes used in 

 Florida for this purpose. 



In greenhouses, renew the soil from an uninfested field 

 or sterilize with live steam under pressure. Shallow beds 

 may be disinfected by applying a weak solution of for- 

 maldehyde, 1 part of the 40 per cent commercial solu- 

 tion in 100 parts of water, using 1 to 1% gals, for every 

 square yard of surface. 



Millipedes. 



The millipedes, or "thousand-legged worms,'' are elon- 

 gate more or less cylindrical creatures, having a distinct 



