Evaluation of Spring Wheat Germplasm for Resistance to Bacterial Leaf Streak Caused by Xanthomonas campestris pv. translucens.

Bacterial leaf streak (caused by Xanthomonas campestris pv. translucens) has reemerged as a potential threat in spring wheat (Triticum aestivum) production areas in the northern Great Plains. As with other foliar bacterial diseases, chemical control under field situations is neither economical nor practical. Development of resistant genotypes will be needed for adequate management of the disease. There is currently limited information on sources of resistance in hard spring wheat germplasm. The main objective was to develop and apply a robust screening tool for evaluating germplasm against bacterial leaf streak, and to identify resistance sources for this disease. Inoculated field experiments were conducted in Brookings and Codington Counties, SD in 2009 and 2010 using a virulent local isolate (XctSD-017) inoculated after tillering stage. Forty-five hard red spring wheat genotypes with diverse genetic backgrounds were evaluated for disease severity, with ratings made at 7-day intervals from heading through dough stage. Results of this study showed clear differences in level of resistance among the 45 genotypes, with no immunity expressed. SD4205 was found resistant to the disease with the lowest area under the disease progress curve across location-years. Other genotypes showing moderate levels of resistance included SD4148, SD4176, 'Alsen', SD4023, 'Faller', SD4024, 'Knudson', and SD4199. Grain weight was negatively correlated to disease, as was days to heading. The resistance identified appeared to be quantitative in nature and was expressed through slower disease progress and reduced severity.