Paras. Qt2 



organisms, it is neither impossible nor especially difficult to obtain 

 these same organisms free from nematodes. One can remove the nematodes 

 from the water in which they are suspended when drawn from the fiinnels, 

 and this fluid can be placed around the roots of control plants or 

 around the roots of a third set of plants provided for the purpose." 

 If a third set of plants is provided, comparisons can be made between 

 the three sets of plants: (1) Controls in sterilized soil; (2) In 

 sterilized soil inoculated with nematodes and associated organisms; and 

 (3) In sterilized soil inoculated with associated organisms without 

 nematodes. If growth in (1) and (3) is equal, while growth in (2) is 

 depressed, the logical assumption is that the decrease in grcr^th is 

 either due to the nematodes alone or to the combination of nematodes 

 and associated organisms. For practical purposes, it makes little 

 difference as it has been shown that the nematodes are an essential 

 member of the complex, and control might be expected to be obtained by 

 their elimination. 



The fact that sting nematode may be an important factor in cotton wilt 

 was shown by Holdeman and Graham (Phytopath. U2(5): 283-28U, of 1952). 

 They collected infested field soil and eliminated sting nematodes from 

 a portion of it by air drying, while a second portion was kept moist. 

 Cotton Fusarium inoculum was added to each lot of soil and wilt-resist- 

 ant and wilt- susceptible cotton varieties were planted. With the sting 

 nematodes, the resistant variety averaged S'^% wilt, compared with no 

 wilt where the nematode was absent. The susceptible variety had an 

 average of 88^ wilt with the sting nematode and only 10^ without it. 



Information on hosts of Belonolaimus can be obtained from Christie ©t 

 at. (loc. cit.) and from Holdeman and Graham (Plant Dis. Reporter 3T(lO): 

 II^T-S'OO, of 1953). Apparently, sting nematodes are capable of feeding 

 on a large variety of plant species, including both crop plants and weeds. 

 As would be expected, certain other species appear to be unsuitable hosts, 

 among them being tobacco, watermelon, and crotalaria. However, establish- 

 ment of a host list for sting nematodes is still in the early stages, and 

 it should be kept in mind that there may be species, subspecies, popula- 

 tions, or races with varying host habits, as have been found with other 

 plant-parasitic nematodes. 



Control of sting nematodes by crop rotation or by soil fiimigation appears 

 to present no special problems. Miller (Phytopath. U2(9): U70, of 1952) 

 reports excellent control with ethylene dibromide at moderate rates of 

 application. VJhen adequate host lists are available, control rotations 

 can be devised. 



