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Evaluation of fungicides for management of rust on oil seed and confection sunflower hybrids

Brandt Berghuis: North Dakota State University

<div>Two types of sunflower hybrids are produced in the United States; oil seed and confection (non oil). In 2016, approximately 0.64 M Ha were planted, 84% of which were oilseed and the remainder confection. Sunflower rust, caused by the fungal pathogen <em>Puccinia helianthi</em>, is an economically important disease of sunflowers. Recent research demonstrated that several fungicides were efficacious and an economically viable management tool for sunflower rust. However, the vast majority of the work was done on the confectionery type sunflowers, widely considered to be more susceptible to the disease. Additionally, many “new” fungicides have recently become available to sunflower growers. The objective of this study is to evaluate the efficacy of new fungicides on oil seed and confection sunflower hybrids for rust management. Oilseed and confection sunflower hybrid trials were planted in four row plots in a Randomized Complete Block Design with four replicates in two locations in 2016 and 2017. Trials were artificially inoculated with <em>Puccinia helianthi</em> urediniospores. Twelve different fungicide treatments were applied at growth stage R5. Rust severity was visually evaluated at growth stage R6 and R7. Significant rust severity differences between fungicides and the non-treated control and among fungicides were observed in all confection and oilseed trials. Efficacy of new fungicides tended to be consistent within FRAC groups and will be useful management tools for growers.</div>