How does drought stress drive pathogenic and mycotoxigenic Fusarium in maize?

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Commodities

• Agronomic: corn

Practices

• Production Systems: agroecosystems, organic agriculture

Drought events in the Northeastern United States are projected to become more frequent putting crops at greater risk of yield loss and increased mycotoxin contamination. Drought stress can directly affect maize (Zea mays) production, reducing kernel set and ear size. An increase in maize susceptibility to disease that involves hot and dry conditions, favor pathogenic and mycotoxigenic fungi from the genus Fusarium, the causal agents of stalk and ear rots (F. verticillioides and F. subglutinans). These fungi also produce mycotoxins which put human and livestock health at risk. To reduce disease and mycotoxin contamination from Fusarium pathogens, transgenic Bt-maize is used, which reduces pest pressure and opportunities for infection of ears and stalks. However, previous studies have demonstrated that Fusarium pathogens and mycotoxin producers can colonize maize leaves asymptomatically and produce mycotoxins even when no disease is visually present and therefore can potentially contribute to the contamination of silage for feed. Silage is a fermented feed product made from chopped ground stalk, ear, and leaf tissue and is at high risk of mycotoxin contamination from Fusarium when infection is high in harvested plant material. It is unclear how drought stress shapes Fusarium spp. in maize leaves, especially pathogenic and mycotoxigenic species. This is critically important for regional maize silage producers who may be disproportionately affected throughout the Northeast by changes in foliar Fusarium spp. communities. This research aims to determine how drought stress shapes foliar pathogenic and mycotoxigenic Fusarium spp. in maize.

1. To determine the interaction between host development, drought stress events, and Fusarium spp. fungal communities of maize.

        a. Assess how the Fusarium spp. community of maize leaves changes across drought exposure events pre- and post-flowering.  

        b. Assess the effect of drought exposure pre- and post-flowering on the functional composition of Fusarium spp. communities.  

        c. Assess the effect of drought exposure pre- and post-flowering on Fusarium spp. communities at harvest for silage.  

2. To reveal the interaction between drought stress events and pathogenic and mycotoxigenic Fusarium spp. in maize at harvest for silage.  

3. To quantify the effect of host genotype and drought on the foliar Fusarium spp. community.