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Research Project: Genetic Improvement of Small Grains for Biotic and Abiotic Stress Tolerance and Characterization of Pathogen Populations

Location: Plant Science Research

Title: Effect of levels of wheat residue on the severity of stagonospora nodorum blotch in winter wheat

Author
item MEHRA, LUCKY - North Carolina State University
item Cowger, Christina
item OJIAMBO, PETER - North Carolina State University

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Proceedings
Publication Acceptance Date: 8/17/2013
Publication Date: N/A
Citation: N/A

Interpretive Summary: Stagonospora nodorum blotch (SNB), caused by the fungus Stagonospora nodorum, is a major disease of wheat. Wheat residue can be an important source of fungal spores to start new epidemics, but the effect of different densities of infected debris on disease severity has not been previously determined. Experiments were conducted in Raleigh and Salisbury, North Carolina, in 2012 and 2013 using the susceptible winter wheat cultivar ‘DG-Shirley’. We applied different amounts of wheat straw to plots of DG-Shirley, resulting in either 0, 10, 20, 30, 60, or 90% coverage of the ground with residue. We assessed disease severity. The amount of residue had a significant effect on disease severity in the following wheat crop. We concluded that SNB is likely to be increased in a susceptible wheat crop if the ground is at least 30% covered with infected wheat residue, and weather is conducive to the disease.

Technical Abstract: Stagonospora nodorum blotch (SNB), caused by the ascomycete fungus Stagonospora nodorum, is a major disease of wheat. Wheat residue can be an important source of inoculum, but the effect of different densities of infected debris on disease severity has not been previously determined. Experiments were conducted in Raleigh and Salisbury, North Carolina, in 2012 and 2013 using the susceptible winter wheat cultivar ‘DG-Shirley’. Four (2012) or six (2013) treatments were applied in a randomized complete block design with five replications. The treatments were 0, 10, 20, 30, 60, and 90% coverage of the ground with residue; 10 and 20% were added in 2013. Whole-canopy disease severity (DS) was assessed three or four times in each plot. Area under the disease progress curve (AUDPC), maximum DS, and yield were subjected to analysis of variance. In Raleigh, AUDPC for the 30 to 90% coverage levels were significantly greater than AUDPC for the 0% coverage level in both years, but there were no significant differences among the 30, 60, and 90% coverage levels (P < 0.05). In 2012 at Salisbury, AUDPC for the 0% level was also significantly lower than 30 to 90% levels; significant differences in AUDPC were observed among the 30, 60 and 90% levels (P < 0.05). In the 2013 Salisbury experiment, AUDPC was higher at the 20% coverage level than in the control, and no differences were observed among the 20, 30, and 60% coverage level at Salisbury, and higher AUDPC at 90% than all other treatments.