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Hansen B, Gilley MA, Berghuis BG, Halvorson J, Friskop AJ, Schatz BG, Kandel H, Fitterer S, Carruth D, Mathew FM, Markell SG. Effect of fungicide and timing of application on management of Phoma black stem of cultivated sunflowers in the United States. Plant Dis 2024. [PMID: 38301222 DOI: 10.1094/pdis-04-23-0770-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
Phoma black stem (PBS), caused by Phoma macdonaldii Boerema (teleomorph Leptosphaeria lindquistii Frezzi), is the most common stem disease of sunflower (Helianthus annuus L.) in the Northern Great Plains (NGP) region of the United States (US). However, the impact of PBS on sunflower yield in the US is unclear, and a near complete absence of information on the impact of fungicides on disease management exists. The objectives of this study were to determine the impact of PBS on sunflower yield, the efficacy of available fungicides, the optimal fungicide application timing, and the economic viability of fungicides as a management tool. Fungicide timing efficacy was evaluated by applying single and/or sequential applications of pyraclostrobin fungicide at three sunflower growth stages in ten field experiments between 2017 and 2019. Efficacy of ten fungicides from FRAC groups 3, 7, and 11 were evaluated in four field experiments between 2018 and 2019. The impact of treatments on PBS were evaluated by determination of incidence, severity, maximum lesion height (MLH), disease severity index (DSI) and harvested yield. Nine of the ten fungicides evaluated, and all fungicide timings that included an early bud application, resulted in disease reductions when compared to the non-treated controls. The DSI was negatively correlated to sunflower yield in high-yield environments (p=0.0004; R2 = 0.3425), but not in low- or moderate- yield environments. Although FRAC 7 fungicides were generally most efficacious, the sufficient efficacy and lower cost of FRAC 11 fungicides make them more economically viable in high-yielding environments at current market conditions.
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Affiliation(s)
- Bryan Hansen
- North Dakota State University, 3323, Plant Pathology, 1402 Albrecht Blvd., Walster Hall 306, Fargo, North Dakota, United States, 58108-6050;
| | - Michelle A Gilley
- North Dakota State Universtiy, Plant Pathology, PO Box 6050, Fargo, North Dakota, United States, 58108-6050;
| | - Brandt G Berghuis
- University of Wisconsin-River Falls, 14755, Department of Plant and Earth Science, River Falls, Wisconsin, United States;
| | - Jessica Halvorson
- North Dakota State University College of Agriculture Food Systems and Natural Resources, 138199, Plant Pathology, NDSU Dept. 7660, PO Box 6050, Fargo, North Dakota, United States, 58108-6050;
| | - Andrew J Friskop
- NDSU, Plant Pathology, Dept 7660, PO Box 6050, Plant Pathology, Fargo, North Dakota, United States, 58108;
| | - Blaine G Schatz
- North Dakota State University, Carrington Research Extension Center, Carrington, North Dakota, United States;
| | - Herman Kandel
- North Dakota State University College of Agriculture Food Systems and Natural Resources, 138199, Plant Science, Fargo, North Dakota, United States;
| | - Scott Fitterer
- BASF SE, 5184, North Dakota Research Farm, Davenport, North Dakota, United States;
| | - David Carruth
- BASF SE, 5184, North Dakota Research Farm, Ludwigshafen, North Dakota, United States;
| | - Febina Merlin Mathew
- North Dakota State University, Plant Pathology, NDSU Dept: 7660. P.O. Box 6050, Fargo, North Dakota, United States, 58108;
| | - Samuel G Markell
- North Dakota State Universtiy, Plant Pathology, NDSU Dept 7660, Box 6050, Fargo, North Dakota, United States, 58108-6050;
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