A large environmental influence on phenotypic estimates of disease resistance and the complex polygenic nature of Fusarium head blight (FHB) resistance in wheat (Triticum aestivum) are impediments to developing resistant cultivars. The objective of this research was to investigate the utility of a detached leaf assay, inoculated using inoculum from isolates of Microdochium nivale var. majus, to identify components of FHB resistance among 30 entries of U.S. soft red winter wheat in the 2002 Uniform Southern FHB Nursery (USFHBN). Whole plant FHB resistance of the USFHBN entries was evaluated in replicated, mist-irrigated field trials at 10 locations in eight states during the 2001-2002 season. Incubation period (days from inoculation to the first appearance of a dull gray-green water-soaked lesion) was the only detached leaf variable significantly correlated across all FHB resistance parameters accounting for 45% of the variation in FHB incidence, 27% of FHB severity, 30% of Fusarium damaged kernels, and 26% of the variation in grain deoxynivalenol (DON) concentration. The results for incubation period contrasted with previous studies of moderately resistant European cultivars, in that longer incubation period was correlated with greater FHB susceptibility, but agreed with previous findings for the Chinese cultivar Sumai 3 and CIMMYT germ plasm containing diverse sources of FHB resistance. The results support the view that the detached leaf assay method has potential for use to distinguish between specific sources of FHB resistance when combined with data on FHB reaction and pedigree information. For example, entry 28, a di-haploid line from the cross between the moderately resistant U.S. cultivar Roane and the resistant Chinese line W14, exhibited detached leaf parameters that suggested a combination of both sources of FHB resistance. The USFHBN represents the combination of adapted and exotic germ plasm, but four moderately resistant U.S. commercial cultivars (Roane, McCormick, NC-Neuse, and Pat) had long incubation and latent periods and short lesion lengths in the detached leaf assay as observed in moderately FHB resistant European cultivars. The dichotomy in the relationship between incubation period and FHB resistance indicates that this may need to be considered to effectively combine exotic and existing/adapted sources of FHB resistance.

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. University of California Press and CooperOrnithological Society are collaborating with JSTOR to digitize, preserve and extend access to The Condor.ABSTRACT. -Behavior, habitat use, and foraging of the Whistling Heron (Syrigma sibilatrix) and Capped Heron (Pilherodius pileatus) were studied in Venezuela and Argentina. Both foraged primarily alone or in pairs, but Whistling Herons also fed and roosted socially. Whistling Herons nested solitarily, maintained post-fledging associations with young, and appeared to defend feeding territories. They foraged in patches of short grass in wet savannas, especially where water was a few centimeters deep. Capped Herons also foraged in wet savanna, but the edges of streams or ponds seemed to be their preferred habitat. Whistling Herons fed by standing and slow walking, usually in an upright posture. At times they waved their heads in an exaggerated manner. Capped Herons crouched for long periods and walked slowly. Although the basic foraging tactics of the two species were similar, differences support the suggestion that the Capped Heron is a bird of forested streams and ponds while the Whistling Heron is a bird of open savanna. In many ways, the Whistling Heron resembles paleotropical grassland herons.

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The soybean cyst nematode (SCN), (Heterodera glycines Ichinohe), is a major pest of soybean [Glycine max (L.) Merr.) and new biotypes have been identified in recent years. A new biotype that reproduces on the ‘Bedford’ cultivar has been identified in Arkansas and is designated as “race X”. The objectives of this research were to study genetics of resistance to race X and measure heritability. Crosses and reciprocals were made between PI 90763, a genotype resistant to race X, and three susceptible genotypes, PI 88788, R74‐1001, and PI 209332. Data from F1, F2, and backcross populations indicate that a single recessive gene conditions resistance in these genotypes. There was no evidence of maternal or cytoplasmic inheritance in any of the crosses. Ninety‐four F3 lines were evaluated for reaction to race X and race 4. Lines that are resistant to race X were susceptible to race 4, and the lines resistant to race 4 were susceptible to race X with correlation coefficients of −0.53 and −0.59, respectively. No F3 lines from these crosses were identified as either highly resistant or susceptible to both race 4 and race X of SCN. Narrow sense heritability estimates based on regression of F3 family means on parental plant values ranged from 61 to 64% for the three crosses. The data indicate that the screening techniques used to determine reaction of individual plants were relatively effective for determining resistance.