GARDEN PESTS IN NEW ZEALAND 



retained in the body of the female, which forms a protective sack or 

 cyst (Fig. 13, 17 and 18), and in this state the eggs pass the winter in 

 the ground, where they are known to remain dormant for a period of 

 ten years; under favourable conditions in the spring, the larvae emerge 

 from the eggs and attack the rootlets of suitable host plants, entering 

 them at the extreme tip. Satisfactory methods of control have not yet 

 been developed under field conditions, but a four-year crop rotation 

 following potatoes is suggested; seed potatoes from infested ground 

 should not be used. 



The roots of tomatoes are often found to be a mass of galls, due to 

 attack by the root-knot eelworm (Heterodem radicicola), which also 

 infests tobacco roots as well as other plants (Fig. 13, 19 and 20). All 

 stages of this species are to be found in the root galls; the female lays 

 her eggs in a gelatinous egg sack, which remains attached to the parent. 

 The larvae, on hatching, either remain within the parent gall or leave it 

 and enter the soil, where they seek out and attack the roots of another 

 plant. In tomato gardens steam sterilisation of the soil is the most 

 effective means of control. 



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