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POSTERS: Postharvest pathology and mycotoxins

Determining a threshold for use of deoxynivalenol (DON) contaminated durum wheat as seed
Audrey Kalil - North Dakota State University Williston Research Extension Center. Taheni Gargouri Jbir- North Dakota State University Williston Research Extension Center, Dimitri Fonseka- North Dakota State University Williston Research Extension Center

North Dakota is the top producer of durum wheat in the United States, harvesting just over 1 million acres in 2018. Epidemics of Fusarium Head Blight (FHB) in recent years have been a severe constraint to production, resulting in mycotoxin contaminated grain unsuitable for use as food or feed. Use of contaminated grain as a seed source is not recommended, due to poor germination and plant vigor. However, data outlining tolerable levels of mycotoxins, functionally corresponding to levels of fungal contamination, in grain used for seed is lacking. Field evaluations of durum seed contaminated with varying levels (< 0.3 – 19.9 ppm) of the mycotoxin deoxynivalenol (DON) were conducted over two years. Treatments were split to assess the effect of the seed applied fungicide, tebuconazole, on plant population and yield. Seeding rates were adjusted to account for poor germination. Seed with greater than 10 ppm DON resulted in stand reductions in one out of two years. Treatments seeded with grain containing 19.9 ppm DON resulted in a 5.3 bu/ac yield decrease in one year of the study. Tebuconazole seed treatment had no effect on plant population or yield. Our data suggest that grain containing less than 10 ppm DON may be used as seed without yield loss. The effect of such a practice within a crop cropping system is still unclear.