TY - JOUR
T1 - Baseline and non-baseline sensitivity of Magnaporthe oryzae isolates from perennial ryegrass to azoxystrobin in the northeastern United States
AU - Ma, B.
AU - Uddin, W.
AU - Olaya, G.
N1 - Funding Information:
We thank Lesli Lucas, Bellie Lucas, and Sook-Yong Park for their assistance in this study. We also thank Gary Moorman and Turner Sutton for critically reviewing the manuscript. Financial support for this study was provided by the Pennsylvania Turfgrass Council and Syngenta Crop Protection.
PY - 2009/3
Y1 - 2009/3
N2 - Gray leaf spot, caused by Magnaporthe oryzae, is chiefly managed by the application of fungicides. Among several systemic fungicides, azoxystrobin has been effectively used to control the disease; however, the development of resistance in M. oryzae to azoxystrobin has been reported in some regions of the United States. The sensitivity level to azoxystrobin of pathogen isolates from perennial ryegrass turf has not been documented in a comprehensive manner in the northeastern United States. This survey was conducted to evaluate the sensitivity to azoxystrobin of 135 isolates of M. oryzae collected between 1995 and 2004 from golf courses primarily in the northeastern United States. Media components, incubation time, and temperature were optimized for a modified in vitro spore germination assay to determine the sensitivity of the isolates. The EC50 value of 111 baseline isolates ranged from 0.001 to 0.083 μg/mL (mean 0.039 μg/mL) and 21 non-baseline isolates from Pennsylvania (PA) ranged from 0.007 to 0.066 μg/mL (mean 0.029 μg/mL). No significant difference in sensitivity (P ≤ 0.05) was observed between baseline and PA non-baseline isolates. DNA sequence analysis of the cytochrome b gene (CYTB) showed that no mutation had occurred among PA non-baseline isolates. The study established azoxystrobin baseline sensitivity for M. oryzae in the northeastern United States and indicated that because of limited use of QoI (quinone outside inhibitor) fungicides and the practice of using fungicide rotations and mixtures for gray leaf spot control, a shift in sensitivity to azoxystrobin has not yet occurred in the PA non-baseline isolates.
AB - Gray leaf spot, caused by Magnaporthe oryzae, is chiefly managed by the application of fungicides. Among several systemic fungicides, azoxystrobin has been effectively used to control the disease; however, the development of resistance in M. oryzae to azoxystrobin has been reported in some regions of the United States. The sensitivity level to azoxystrobin of pathogen isolates from perennial ryegrass turf has not been documented in a comprehensive manner in the northeastern United States. This survey was conducted to evaluate the sensitivity to azoxystrobin of 135 isolates of M. oryzae collected between 1995 and 2004 from golf courses primarily in the northeastern United States. Media components, incubation time, and temperature were optimized for a modified in vitro spore germination assay to determine the sensitivity of the isolates. The EC50 value of 111 baseline isolates ranged from 0.001 to 0.083 μg/mL (mean 0.039 μg/mL) and 21 non-baseline isolates from Pennsylvania (PA) ranged from 0.007 to 0.066 μg/mL (mean 0.029 μg/mL). No significant difference in sensitivity (P ≤ 0.05) was observed between baseline and PA non-baseline isolates. DNA sequence analysis of the cytochrome b gene (CYTB) showed that no mutation had occurred among PA non-baseline isolates. The study established azoxystrobin baseline sensitivity for M. oryzae in the northeastern United States and indicated that because of limited use of QoI (quinone outside inhibitor) fungicides and the practice of using fungicide rotations and mixtures for gray leaf spot control, a shift in sensitivity to azoxystrobin has not yet occurred in the PA non-baseline isolates.
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U2 - 10.1080/07060660909507572
DO - 10.1080/07060660909507572
M3 - Article
AN - SCOPUS:77955915188
SN - 0706-0661
VL - 31
SP - 57
EP - 64
JO - Canadian Journal of Plant Pathology
JF - Canadian Journal of Plant Pathology
IS - 1
ER -