Autor: |
Friskop AJ; Department of Plant Pathology, North Dakota State University, Fargo 58102., Gulya TJ; USDA-ARS Northern Crop Science Laboratory, Fargo, ND 58108., Halley SA; North Dakota State University, Langdon Research Extension Center, Langdon 58249., Schatz BG; North Dakota State University, Carrington Research Extension Center, Carrington 58421., Schaefer JP; CHS Sunflower, Grandin, ND 58038., Jordahl JG, Meyer SM; Department of Plant Pathology, North Dakota State University, Fargo 58102., Misek KW; North Dakota State University, Langdon Research Extension Center, Langdon 58249., Hendrickson P; North Dakota State University, Carrington Research Extension Center, Carrington 58421., Markell SG; Department of Plant Pathology, North Dakota State University, Fargo 58102. |
Abstrakt: |
Sunflower rust is an important yield-limiting disease in sunflower production in the Great Plains of the United States. Rust severity and incidence have increased between 2002 and 2011, and genetic resistance is limited in most commercial hybrids, particularly the high-value confectionary market type. Although fungicides are available for rust management in the United States, management recommendations are insufficient. Specifically, efficacy and timing data are very limited for fungicides in FRAC groups 7 and 11. Seventeen fungicide efficacy and timing trials were conducted between 2008 and 2011 in North Dakota. Timings evaluated across the four years included single or multiple applications at growth stages (GS): GS V8-V12 (late vegetative), GS R1 (terminal bud formation), GS R3-4 (elongation of bud), GS R5 (flowering), and GS R6 (completion of flowering). With few exceptions, fungicide applications of DMIs and QoIs controlled disease greater than SDHI fungicides. Fungicide applications made at R5, either singly or in combination, consistently resulted in greater disease control. A negative correlation (r = -0.7756) between disease control and yield was observed, resulting in a yield reduction of 6.6% for every 1% increase in disease severity. |