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Is increased inoculum for Fusarium graminearum an unintended consequence of stay green maize?

Katiani Eli: University of Guelph, Ridgetown Campus

<div>The potential for <em>Fusarium graminearum</em> infection and mycotoxin accumulation in maize and wheat may be increasing with trends in modern maize production. Stay green hybrids are bred to stay physiologically active for a longer period, resulting in increased grain yield. Stay green hybrids stalks may present higher carbohydrate content at harvest, compared to those that senesce earlier and closer to physiological grain maturity. This delay in canopy senescence may accelerate the colonization of <em>Fusarium</em> spp. in fresh stalks after harvest, favoring the development of inoculum and its overwintering on stalks. Coincidently with the introduction of stay green hybrids, it has recently become more common to observe stalks blackened by perithecia soon after maize harvest rather than in the spring, as observed in previous years. The objective of this study is to investigate the relationship between residual carbohydrates and moisture in modern maize hybrids with inoculum production and timing. In this study, 50 commercial hybrids representing a range of stay green characteristics were tested for soluble solids, total solids and moisture content in maize stalks immediately after grain harvest. These stalks will be monitored for perithecia timing of development and their abundance in the spring, and then assessed for ascospore production during winter wheat and maize flowering, comparing inoculum potential of hybrids with differing stay green properties. Results will be presented.</div>