The Response of Fusarium graminearum-Infected Seed of Hard Red Spring Wheat to Vitavax Extra RTU and Dividend XL Seed Treatments

Fusarium head blight (FHB) caused by Fusarium graminearum can severely impact seed quality and limit the availability of seed. Repeated outbreaks of FHB in the hard red spring wheat (HRSW) production areas of Minnesota and North Dakota since 1993 has forced seed dealers and producers, on occasion, to use FHB-infected wheat as seed. In this experiment, two FHB-infected seed lots, one of the variety Verde and one of the variety 2375, were used to determine the effect of Vitavax Extra RTU (16.7% carboxin : 1.2% imazalil : 1.5% thiabendazole) and Dividend XL (16.5% difenoconazole : 1.38% mefenoxam) on initial plant population, grain yield, and quality. The standard laboratory germination tests indicated that germination of Vitavax Extra RTU-treated seed increased germination from 64 to 84% for both seed lots. Using a four-by-two factorial design, the effect of the brand of seed treatment, the effect of using either brand of seed treatment versus not using a seed treatment at all, and the attained germination percentages from the laboratory tests were used to determine the effects on the initial plant population, grain yield, test weight, and grain protein content. In three field trials, there was no significant interaction between the use of either Vitavax Extra RTU or Dividend XL and seeding rate for initial plant population, grain yield, and test weight. Although a treatment of FHBinfected wheat seed with Vitivax Extra RTU increased germination in a laboratory test, there was no increase in initial plant population or grain yield and quality compared to untreated seed. However, increasing the seeding rate in field trials compensated for poor germination results in the laboratory test and resulted in higher initial stands. Consequently, results of the laboratory test of the untreated seed needed to be used to calculate a proper seeding rate for both seed lots.