Determining the basis of pyraclostrobin activity against Pythium root dysfunctionconcentrations

Pyraclostrobin has shown good to excellent control of Pythium root dysfunction of creeping bentgrass caused by Pythium volutum. Experiments were conducted to determine if disease suppression was due to fungicidal effects or physiological effects on the host. Sensitivity in culture was examined using...

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Bibliographic Details
Published in:Phytopathology 2006-06, Vol.96 (6), p.S60-S60
Main Authors: Kerns, J P, Tredway, L P
Format: Article
Language:English
Subjects:
Pythium
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Summary:Pyraclostrobin has shown good to excellent control of Pythium root dysfunction of creeping bentgrass caused by Pythium volutum. Experiments were conducted to determine if disease suppression was due to fungicidal effects or physiological effects on the host. Sensitivity in culture was examined using twelve isolates of P. volutum, five isolates of P. torulosum, and one isolate of P. aphanidermatum. Isolates were plated on five concen-trations of pyraclostrobin, azoxystrobin, and mefanoxam. Average EC sub(50) values for three P. volutum isolates were 0.012, 0.30, and 0.46 mg kg super(-1) for pyraclostrobin, azoxystrobin, and mefanoxam respectively. Growth chamber studies were conducted to determine if pyraclostrobin influences foliar growth of creeping bentgrass. Treatments consisted of four nitrogen levels and seven pyraclostrobin rates. Pyraclostrobin applications did not significantly increase creeping bentgrass growth rate. All isolates of P. volutum, except for one, were sensitive to all three fungicides tested, but considerable variation among isolates was detected. Variation in fungicide sensitivity among P. volutum isolates may explain differences in fungicide efficacy across locations.
ISSN:0031-949X