Contro] Aj9 



Where a high value crop is planted, prospective retiirns fjrom the fumiga- 

 tion must be considered* Since this depends on the nematode population 

 of the field, Information on this point is desirable, but often difficult 

 to obtain. 



If the nematodes are one of the root-knot species and a susceptible crop 

 is growing in the field, it is easy to get a fairly accurate idea of the 

 size of the population by examination of the roots of the plants. But 

 if syii5)toms of attack are not so readily recognized, or no crop is grow- 

 ing on the field, the task is more difficult. 



Theoretically, it should be possible to estimate the nematode population 

 of a field by examination of soil samples. In practice, attempts to 

 apply this method reveal a number of difficulties. The first of these 

 is obtaining and examining an adequate sample of the field. Examination 

 of a sufficient number of soil samples simply requires more time than is 

 usually available. And, even if an accurate estimation of the nematode 

 population can be made, the background information necessary to correlate 

 such findings with subsequent crop growth is largely lacking. 



In case of doubt, the grower should be encouraged to experiment on his 

 own farm. That is, he shoixld be advised to use soil fumlgants on a 

 trial basis, in such a way that easy comparisons between fumigated and 

 vuifumigated soil are possible. 



