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Use of fungicides to enhance grain yield and reduce disease levels in cultivated wild rice

Deborah Samac: USDA-ARS


<div>Attaining high grain yields in cultivated wild rice is frequently hampered by fungal diseases mostly caused by <em>Bipolaris</em> spp. In 2013, 2014, and 2015 grain yield reductions occurred, with losses as high as 33.5% compared to years of low disease pressure. An integrated disease management system has been implemented, but the limited disease resistance available in cultivars cannot cope with the disease pressure that often occurs and growers must rely on fungicides. The two most used fungicides contain azoxystrobin (targets fungal respiration) alone or in combination with propiconazole (disrupts the ergosterol biosynthesis pathway). The objective of this study was to evaluate the effectiveness of these fungicides to control foliar diseases in wild rice paddies. We conducted on farm experiments in 2016 and 2017 in four Minnesota locations. Fungicides were used in single or combined applications, with an untreated control under natural fungal infection. Percent diseased leaf area was determined in upper leaves in each treatment. Application of fungicides enhanced grain yield and decreased the level of foliar diseases in the upper leaves, although statistically significant differences (<em>P</em><0.05) among treatments for both variables were not observed in all the years and locations. Disease severity and grain yield were negatively correlated. Responsible use of fungicides can reduce foliar diseases and enhance grain yield in cultivated wild rice.</div>