H. glycines:5 



About three months after planting, the plants in the Nemaf;on plot 

 treated at 5 gallons per acre were about shoulder hi . They were 

 very green in color and gave one of the highest yields. 



We made a larval emergence study throughout the year, taking samples 

 every month. We were particularly interested in the build-up of the 

 nematode during the growing season. At the end of the growing season, 

 we took samples from all of the plots, recovered the cysts and let the 

 larvae hatch out in Baermann funnels. The counts represented the nvm- 

 ber of larvae per half -pint of soil. The check plots yielded alm.ost 

 the lowest larval counts; not the lowest, but very low. One vjould 

 expect this, because of the very poor plant growth during the season. 

 The nematodes presimably did not have enough root system available to 

 them. 'Te did find relatively few larvae in the methyl bromide plots. 

 We do not know if these represent forms missed in the white cyst checks 

 made earlier at one month, or whether they were due to contamination. 

 It was very difficult to takj care of the plots in such a way as to 

 avoid the possibility of contamination. There was some build-up of the 

 population in the Telon treated plots, larva counts being very high in 

 the 20 gallon rate plot. D-D and, again, the ethylene debromide gave 

 somewhat eratic results and, in general, fairly poor control of the 

 nematode build-up. 



The final aspect of the experiment was the yield of beans. The plots 

 were, as mentioned, 20 feet square with 8 rows of plants. Yield data 

 were taken on the center h rows. The untreated checks yielded some- 

 thing like 7 bushels of beans per acre. Some of the better treatment 

 plots had yields of about 22 to 23 bushels per acre. Allof the yields 

 were better than those of the checks, although not substantially so in 

 all cases. F --st treatments gave fairly good yields. Poor yields were 

 found in the Telon plots and in some of the D-D treated plots. 



Another phase of the overall work has been a study of resistance. The 

 first year, 1956, two or three thousand lines of soybeans were tested 

 in these infested fields in the search for resistance. This work has 

 been carried on jointly, with Dr. Herb Johnson of the U.S.D.A. working 

 with Dr. Skotland and Dr. Ross, at Raleigh, North Carolina, Last year 

 as far as I know, none of the tested lines shov/ed any resistance; but 

 this year, out of some 29 hundred lines screened, they have run across 

 about seven or eight promising lines. >/hen I talked to Dr. Ross last, 

 he said there were between two and five lines that look extremely good. 



I would like to say a little about this screening work. The field used 

 was checked before planting and found to be highly infested with the 

 soybean cyst nematode. The plant lines to be tested were planted in 

 short rows five feet long. In order to make sure the plants were ex- 

 posed to infection and were not just "escapes," along side each plant 

 being tested there was planted a known susceptible plant. These indi- 

 cator plants vjere of a glaborous type, so as not to be mixed with the 

 plants under test. Thus, if the indicator plant had roots well covered 

 v;ith cysts, and the adjacont test olant did not, there could bo some 



