Challenges and solutions for stripe rust control in the United States

Stripe rust of wheat, caused by Puccinia striiformis f. sp. tritici, has been one of the most destructive diseases on wheat in the western USA since the late 1950s and has become increasingly important in the central and south-eastern USA since 2000. Stripe rust of barley, caused by P. striiformis f. sp. hordei, a relatively new disease, has established and caused severe damage in the south-central and western states since the pathogen was first reported in Texas in 1991. Stripe rusts of wheat and barley have been monitored by trap nurseries and by. eld surveys. Collections of stripe rust from wheat, barley, triticale, and grasses have been tested on a set of 20 wheat differential genotypes for identifying races of P. striiformis f. sp. tritici and a set of 12 barley differential genotypes for identifying races of P. striiformis f. sp. hordei. In total, 62 new races of P. striiformis f. sp. tritici and 22 new races of P. striiformis f. sp. hordei have been identified since 2000. Germplasm and breeding lines of wheat and barley have been tested every year under natural infection in the. eld and with selected races in the greenhouse. Combinations of durable high- temperature, adult-plant resistance with effective all-stage resistance should provide more effective stripe rust control and reduce the use of fungicides.