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'USDA Fortress' (Reg. no. CV‐375, PI 696161), a multiple aphid‐resistant, high yielding, six‐rowed, mid‐season–maturing, winter feed barley (Hordeum vulgare L.) adapted to the Southern Plains, was developed and released by USDA‐ARS in Stillwater, OK. USDA Fortress is highly resistant to Russian wheat aphid [RWA; Diuraphis noxia (Kurdjumov)] and greenbug [Shizaphis graminum (Rondani)], with seedling resistance to the new invasive pest, hedgehog grain aphid [HGA; Sipha maydis (Passerini)]. USDA Fortress has the pedigree 'Post 90' *4/R012. Recurrent parent Post 90 has Rsg1 resistance to greenbug, and R012 is an unadapted RWA‐resistant germplasm line selected by USDA‐ARS Stillwater from PI 10706. Post 90 and USDA Fortress rate 2 on Starks' greenbug resistance scale of 1–9, while USDA Fortress and R012 rate a 3 on Websters Russian wheat aphid resistance scale of 1–9, where 1 is immune and 9 is dead on both scales. Over 17 location‐years, in the absence of aphids, grain yield of USDA Fortress was 19 and 12% greater than 'Thoroughbred' and Post 90, respectively. USDA Fortress has average test weight of 60 kg hl–1 and has stable grain yield over state‐wide variability in climatic conditions. USDA Fortress is the first multiple‐aphid resistant barley cultivar in the United States. Core Ideas: USDA Fortress has a high level of resistance to multiple aphid pests of barley.USDA Fortress is high yielding across varied climatic conditions.USDA Fortress is a non–genetically modified organism feed barley competitive with other feed grains for forage. [ABSTRACT FROM AUTHOR]

Infestations of Russian wheat aphid (RWA), Diruaphis noxia (Mordvilko), reduce grain yield and quality of barley, and have induced producers in some areas to cease growing barley (Hordeum vulgate L.). No RWA-resistant barley cultivars that are adapted to North America exist. Resistance from the germplasm line STARS 9301B was transferred into adapted germplasm via backcrossing. Our objective was to determine the potential utility of this resistance for the protection of yield and malting quality in adapted germplasm. We studied the effect of RWA infestations on grain yield and malting quality of STARS 9301B, the susceptible adapted parents 88Y315 and 'Garnet', and five backcross-derived progeny. Four of the backcross-derived lines were rated as highly resistant and one as moderately resistant, and were superior to STARS 9301B and similar to their recurrent parents with respect to agronomic performances and, to a lesser extent, malting qualities. When infested at the boot to heading stage, STARS 9301B, and the highly resistant progeny lines had negligible reductions in agronomic performances and malting qualities; slightly greater reductions were observed for the susceptible parents and the moderately resistant progeny line. When infested at the three-to six-leaf stage, STARS 9301B and the resistant backcross-derived lines showed relatively small reductions in their agronomic performances and malting qualities. In sharp contrast, however, the susceptible parents, and to a lesser extent the moderately resistant progeny line, showed moderate to severe leaf streaking and rolling, head trapping, and reductions in their agronomic performances and malting qualities. STARS 9301B should provide a valuable source of resistance to RWA damage., THE RUSSIAN WHEAT APHID has caused over $1 billion in losses in the western USA since it was first identified in Texas in 1986. No biotypic variation has been discovered [...]

Greenbug (Schizaphisgraminum Rondani) is one of the aphids causing significant cereal yield losses worldwide, and greenbug Biotype H is virulent to all known greenbug resistance genes in barley (Hordeum L.). Wild barley (Hordeum vulgare ssp. spontaneum) accession WBDC336 (PI 682028) exhibits resistance to greenbug Biotypes C, E, H, I, WY81, WY12 MC, and WY86. To investigate the genetics of greenbug resistance in WBDC336, a recombinant inbred line (RIL) population was developed from the cross Weskan × WBDC336. The RIL population was evaluated for responses to greenbug Biotype E and genotyped using genotyping‐by‐sequencing. Among 67,238 single nucleotide polymorphisms (SNPs) identified, 3,907 high quality SNPs were selected for gene mapping after several filtering steps. Linkage analysis positioned the greenbug resistance gene to a 1.14‐Mb interval in the terminal region of the long arm of chromosome 3H in WBDC336, where the greenbug resistance gene Rsg1 resides. Greenbug assays and an allelism test indicated that the greenbug resistance gene in WBDC336 is likely an allele at the Rsg1 locus and was given the allele designation Rsg1.a3. Two Kompetitive allele‐specific polymerase chain reaction (KASP) markers were developed from SNPs closely linked to Rsg1.a3, and these markers can be used to tag both alleles at the Rsg1 locus in breeding program utilizing marker‐assisted selection. Core Ideas: The first barley gene conferring resistance to greenbug Biotype H was identified in WBDC366.The greenbug resistance gene in WBDC366, designated Rsg1.a3, is likely allelic to Rsg1.Two KASP markers closely linked to Rsg1.a3 were developed for marker‐assisted selection. [ABSTRACT FROM AUTHOR]

Most biotypes of the greenbug [Schizaphis graminum (Rondani)] are extremely damaging to barley (Hordeum vulgate L.). However, greenbug biotype G has been reported to be unable to successfully feed on barley, and is described as the first greenbug avirulent to 'Wintermalt' barley (which is susceptible to all other greenbug biotypes). The objective of this study was to determine the pest status of greenbug biotype G in barley by characterizing the response of select barley cultivars and germplasm to greenbug biotype G feeding. Eight barley and four wheat (Triticum aestivum L.) cultivars and germplasm were challenged with biotype G and damage ratings recorded after 22 d of infestation. Barley is indeed a host of biotype G and genetic diversity exists within barley for reaction to attack by greenbug biotype G. Three barley cultivars were killed by biotype G, while five were resistant to feeding damage. These new sources of resistance to greenbug biotype G in barley should prove useful in the development of new greenbug-resistant barley cultivars., THE GREENBUG IS AN economically important pest of barley in the USA (Starks and Webster, 1985). A 1942 greenbug outbreak that caused an estimated $38 million yield loss in small [...]

Sipha maydis Passerini (Heteroptera: Aphididae) is a cereal pest with an extensive geographical range that includes countries in Europe, Asia, Africa, and South America. Reports of S. maydis in the United States have been infrequent since it was first detected in California, 2007. Two studies, focused (NW CO) and multistate (OK, TX, NM, CO, UT, WY), were conducted to determine the distribution and host range of S. maydis in the Rocky Mountain and Southern Plains states over a 3-yr period, 2015–2017. In 2015, focused sampling in NW Colorado found S. maydis at 59% of the 37 sites, primarily on wheat. Sipha maydis did not survive extreme winter temperatures from late December 2015 to early January 2016 that ranged from −9.0 to −20.9°C over a 9-d period, which resulted in no aphids detected in 2016. In the multistate study, S. maydis occurred in 14.6% of 96 sites sampled in 2015, 8% of 123 sites in 2016, and 9% of 85 sites in 2017 at wide range of altitudes from 1,359 to 2,645 m. Sipha maydis occurred mainly in NW and SW Colorado and NE New Mexico along with a few sites in NE Colorado, SE Utah, and SE Wyoming. This aphid mainly infested wheat followed by a variety of eight wild grass species. No parasites, predators, sexual morphs, or significant plant damage occurred at the sites. Sipha maydis utilized 14 hosts in the United States including 8 new host records, which expands its host range to 52 plant species worldwide. Sipha maydis may be of concern to wheat, barley, and sorghum production in the United States if its populations continue to increase. [ABSTRACT FROM AUTHOR]

The genetic sources for host-plant resistance to the greenbug (Schizaphis graminum Rondani) in barley (Hordeum vulgare ssp. spontaneum) are limited in that only two single dominant genes Rsg1 and Rsg2 are available for the complex of greenbug biotypes. We evaluated four new barley lines from the Wild Barley Diversity Collection (WBDC) that previously showed potential for greenbug resistance. Three of those entries, WBDC 53, WBDC 117, WBDC 336, exhibited very dominant sources of resistance to older known biotypes B, C, E, F, H, I, and TX1, which also add to the host-plant differentials used to separate these greenbug biotypes. We also re-evaluated the earlier known set of greenbug biotypes that have been in culture for several years against the known host-plant differentials, and included seven newer greenbug isolates collected from Wyoming to the full complement of small grain differentials. This resulted in the discovery of five new greenbug biotypes, WY10 MC, WY81, WY10 B, WY12 MC, and WY86. Wyoming isolates WY4 A and WY4 B were identical in their phenotypic profile, and should be combined as a single unique greenbug biotype. These barley trials resulted in finding new sources of host-plant resistance, although more research needs to be conducted on what type of resistance was found, and how it can be used. We also document that the Wheatland, Wyoming area serves as a very conducive environment for the development of new greenbug biotypes. [ABSTRACT FROM AUTHOR]

The impacts of climate change may increase the duration and frequency of droughts, which would have deleterious effects on crop establishment. The objectives of this study were to determine the effects of moisture stress on seed germination and seedling growth of six winter barley (Hordeum vulgare) lines and discuss how the data are used to select plant materials for rapid germination. Twenty-five seeds of each line were germinated in water of potentials of −2.0, −1.6, −1.2, −0.8, −0.4, and 0 MPa for 4- and 7-days. The experimental design was a factorial arrangement of treatments (barley lines and water potential treatments) in a randomized block replicated four times and repeated twice. The 4- and 7-day percentage seed germination varied with line (p < 0.01), water potential treatment (p < 0.01), and line × treatment interactions (p < 0.01). The seed germination rate varied with water potential treatment (p < 0.01), and line × treatment interactions (p < 0.01). The data indicated that enough variation was present to effectively select and breed cultivars for improved germination at a negative water potential. Studying seed germination under moisture stress is the first step for developing an effected selection pressure for identifying plant materials with rapid seed germination. [ABSTRACT FROM AUTHOR]