H. glycines :2 



have some means of being relatively sure that the nematode was the 

 soybean cyst nematode and not H. trifolii . Dr. H. Hirschmann of our 

 staff was given the assignment. This work has been completed and 

 published. 



Definite differences have been found and recorded between these two 

 species. The differences are evident in the second stage larvae. 

 There were no statistical differences in the cyst characters. Fortu- 

 nately, in the second stage larvae, differences, which never over-lap, 

 were foimd for several characters. These are as follows: the overall 

 length of the nematode, the length of the stylet, the distance from 

 the stylet knobs back to where the dorsal gland empties into the lumen 

 of the esophygus, and the tail length. 



The next phase of the work was to learn something about the nematode's 

 biology. For the most part, Dr. G. B. Skotland, who is a plant pathol- 

 ogist with U.S.D.A., did this work. He made a study of the life history 

 mainly by staining roots in the various developmental stages, using 

 the osmio acid technique. This work has also been published. He found 

 that there were mature males in ih days after infection and that the 

 complete life cycle, under the conditions he performed experiments, was 

 completed in 21 days. 



Another line of work immediately started was, of coiirse, a host range 

 study. This was initiated to enable us to advise the growers, in the 

 particular region of infestation, of crops that they co\ild grow which 

 would not build up the soybean cyst nanatode. First tested were all 

 of the crops that are commonly groim in the area, plus others. By no 

 means is the host range study complete. It is being continued at North 

 Carolina, as well as at some other institutions, now that the soybean 

 cyst nematode has been found elsewhere. 



By and large, the host range of this pest is rather restricted. Appar- 

 ently it is not as limited as for H. rostochiensis and some of the 

 other cyst forms, but the positives are relatively few. The nematode 

 reproduces by far the best and most rapidly on soybeans. Soybeans 

 undoubtedly are a very suitable host. Snapbeans also are infected, and 

 the nematode reproduces, but not to the same extent as on soybeans. 

 Lespedeza and vetch are also hosts, but to a still lesser degree than 

 snapbeans or soybeans. At least, that is the way we feel about it now. 

 irtfe have not run extensive tests comparing the relative host suitabilities 

 of these crops, but I think we can be reasonably safe in saying that 

 soybeans are by far the most suitable host among crops grown in this 

 country at least. 



Some of this work on host range had been done earlier by Ichinohe in 

 Japan. Dr. Skotland has more or less confinned some of the hosts, and 

 he has added new ones to the list. 



■'ffe are also interested in how or what the effects of desication might 

 be on the nematode. We know that cysts' forms are commonly spread in 



