Improvement of emergence and performance of plants derived from red-smudged durum wheat seed by fungicide seed treatments

A controlled-environment study was conducted to determine the effectiveness of eight fungicide seed treatments registered in Canada in improving the emergence, growth and performance of durum wheat ‘AC Navigator’ seedlings and plants derived from red-smudged seed (Pyrenophora tritici-repentis). There were three untreated controls consisting of infected and uninfected seed grown in the greenhouse or in the field. Seedling emergence was reduced in the untreated infected control compared with the untreated uninfected controls. Relative to the untreated red smudge control, all fungicide treatments, except for Dividend XL RTA (difenoconazole and metalaxyl-M), improved seedling emergence. However, no fungicide treatment resulted in emergence as high as in the untreated uninfected controls. In all treatments, lack of seedling emergence was attributed mostly to post-germination death and poor vigour. Compared with the untreated red smudge control, most fungicide treatments did not improve the seedling and plant growth parameters measured in this study. Total number of spikes was lower in plants derived from untreated infected than from uninfected seed or from seed treated with Dynasty 100FS (azoxystrobin). The number of spikes with fully formed kernels was higher in plants derived from uninfected seed or from seed treated with Dynasty 100FS or Raxil T (tebuconazole and thiram) than in plants derived from untreated infected seed. The number of kernels was also lower in plants derived from untreated infected than from uninfected seed or seed treated with Dynasty 100FS. Grain yield was lower for plants in the untreated infected than uninfected control, while yield in the latter was similar to the yield of plants in the Dynasty 100FS, Raxil MD (tebuconazole and metalaxyl), or BASF experimental product treatments. Overall, Dynasty 100FS was most effective in consistently improving the performance and productivity of durum wheat plants derived from red-smudged seeds.