Protein patterns obtained by two-dimensional polyacrylamide gel electrophoresis for three isolates of Heterodera glycines from southern Indiana appear qualitatively similar and have higher pairwise Jaccard similarity coefficients with each other than with isolates from northern Indiana. Three isolates from three northern counties share proteins not present in the southern isolates, but as a gro...

One hundred thirty-nine cultivars of soybean (Glycine max) in Maturity Groups V, VI, VII, and VIII were evaluated in a greenhouse for resistance to Heterodera glycines races 3 and 14 and Meloidogyne incognita, M. arenaria, and M. javanica. Of the cultivars tested, 37% had resistance to H. glycines race 3 alone, 12% had resistance to both races 3 and 14, and 69% exhibited a moderate or high leve...

Field and greenhouse experiments showed that yield losses of sugarbeet, Beta vulgaris, did not occur in soil infested with fewer than eight Heterodera schachtii eggs/g soil. However, larger population densities greatly reduced sugarbeet yield. In the field experiment, the yield in microplots inoculated with more than 64 eggs/g soil was less than 20% of yields in uninoculated microplots. Neverth...

A series of greenhouse experiments was conducted to elucidate the postinfection development of Heterodera glycines in response to applications of alachlor and fenamiphos. The rate of H. glycines maturation on a susceptible soybean cultivar was not altered by 1.0 mug alachlor/g soil but was completely inhibited by 1.0 or 1.5 mug fenamiphos/g soil. An alachlor-fenamiphos combination allowed devel...

Five populations of Heterodera schachtii Schm. from Oregon, Idaho, and Utah did not differ significantly in seedling penetration and rate of emergence and virulence. Another Utah H. schachtii population (Utah 2), however, differed from these five populations in all of the above-mentioned characteristics. More H. schachtii larvae of the Utah 2 population than the other populations penetrated sug...

The sugarbeet cyst nematode, Heterodera schachtii Schmidt, 1871, was discovered by Mai et al. (4) in fields of 16 New York State commercial red table beet growers during a survey in 1970-1971. They reported that the clover cyst nematode, H. trifolii Goffart, 1932, which also has lemon-shaped cysts with bullae, was present in very low numbers in many of the fields sampled. Thus a rapid and relia...

Additional tests of 178 cultivars and lines of soybean against soybean cyst nematode are reported. Cultivars are available with some level of resistance to races 1, 2, 3, 4, 5, 6, 9, and 14, but in some cases the resistance level is moderate. No cultivar or line (except possibly PI 437654) has resistance to all of the races tested. Thirteen cultivars and lines, however, were resistant or modera...

Effects of a mixture of the postemergence herbicides acifluorfen and bentazon, and simulated defoliation expected from green cloverworm on population densities of Heterodera glycines were determined in field plots in Iowa. The herbicide mixture and defoliation each suppressed soybean growth. Population densities of H. glycines were generally lower in herbicide-treated than untreated plots. Popu...

Female indices were measured on six soybean cultivars with resistance to Heterodera glycines derived from PI 88788. Cultivars were inoculated with four isolates of race 6, 3 of race 9, 2 of race 4, and one of race 14. Changes in female index from slightly < or > 10% of the test cultivars compared to 'Lee' resulted in a change of most of the race designations after at least three generations on ...

Population development of isolates of Heterodera lespedezae from Illinois and North Carolina was compared on Korean, sericea, and striate lespedezas and red clover at soil temperatures of 14, 18, 22, 26, 30, 34 C (+/- 1 C) and in a greenhouse where temperatures ranged from 19 to 40 C (av. 25 C). Cyst production on all plants, but not at all temperatures, was significantly different between the ...