H. glycines si 



HET^ODERA GLYCINES , THE PRES^iOT SITUATION 

 J. N. Sasser 



The soybean cyst nematode, Heterodera gylcines , we know is present in 

 Japan, China, and Manchuria. Up until August of 195U, it was known 

 only to occur in the orient. There it causes a disease known as 

 "yellow dwarf." The term is very characteristic of the symptoms in 

 the field. Considerable work has been done by the Japanese workers, 

 particularly Ichinohe and his co-workers. We have had dificulty, 

 however, in getting all of those publications from abroad and even 

 more difficulty in getting them translated. Most of the work that I 

 will report on today, by necessity, will be the work that we have done 

 in North Carolina, as there was no other source from which to make a 

 review. 



The pest was found, as is usually the case, by a grower noticing poor 

 spots in his field over a period of several years. He finally called 

 in one of the plant pathologists at the station within a few miles of 

 this area. Upon examination of the root in the laboratory, niimerous 

 nematode cysts were foimd and were later identified to be H. glycines . 



Immediately after its finding, we were concerned about knowing how 

 widely distributed it was. Our own research staff made a rather hurried 

 survey. It was found that the nematode was rather widely spread within 

 that one community. That is, it was not limited to one field, but 

 there was a rather \Kiiform infestation through several hundred acres. 

 To find out ±i the nematode was spread into our major soybean produc- 

 ing region and how extensively or how widespread it was in the partic- 

 ular region where it was foimd, the Plant Pest Control group from 

 Washington came to make a survey. 



The present extent of the known infested acreage in this one area in the 

 state is now something over 1800 acres. Although the disease at that 

 time was rather minor with us, causing only a very small percentage of 

 the total nematode damage in the state, we did realize its implications, 

 the possibility of spread and the potential threat it might be to the 

 soybean industry. Therefore, we tried to do as much work as we could 

 id.th the facilities and manpower that we had. 



One of the first tasks that we realized as necessary was to be able to 

 accurately distinguish the species. We have known for sometime that 

 H. glycines and H. trifolii very closely resemble each other morpho- 

 logically, and we knew that we had H. trifolii throughout the state on 

 clover . 



The first test was to set about finding definite morphological differ- 

 ences between those two because of the possibility of quarantine action. 

 We knew that if cysts were found on a given pronerty, we would need to 



