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245 1 0 _aDynamics of fungicide sensitivity in Venturia effusa and fungicide efficacy under field conditions
490 0 _vPlant Disease, 102(8), p.1606-1611, 2018
520 3 _aVenturia effusa, which causes pecan scab, has developed resistance to fungicides that were once effective. Over 2 years, laboratory-based sensitivity of fentin hydroxide (TPTH)and tebuconazole in V. effusa and their efficacy under field conditions were compared. Leaf and nut scab were assessed on pecan trees receiving 10 applications of TPTH, tebuconazole, azoxystrobin, azoxystrobin plus tebuconazole, TPTH plus tebuconazole, or no fungicide (NTC)per year. Sensitivity of V. effusa on leaflets collected from treated and nontreated trees was assessed in June and September, respectively. The mean relative germination (RGe)on TPTH at 30 µg/ml was 10.9 and 40.9 percent in 2016 and 4.2 and 0.6 percent in 2017. Mean relative growth (RGr)on tebuconazole at 1 µg/ml was 45.5 and 34.6 percent in 2016 and 69.3 and 56.3 percent in 2017. In both years, leaf and nut scab were significantly lower on trees treated with azoxystrobin, azoxystrobin + tebuconazole, or TPTH + tebuconazole when compared with NTC and tebuconazole-treated trees. Compared with the NTC, tebuconazole did not significantly reduce leaf scab in 2017 or nut scab in either year, indicating that an RGr value between 34.6 and 69.3 percent is likely to result in a control failure on tebuconazole-treated trees. Although better activity was expected, TPTH reduced scab with RGe values between 0.6 and 40.9 percent. These results are valuable for developing fungicide sensitivity thresholds to better predict fungicide performance.
650 1 4 _aFUNGICIDE
700 1 2 _aStandish, J. R.
700 1 2 _aBrenneman, T.
700 1 2 _aStevenson, K. L.
856 4 0 _uhttps://drive.google.com/file/d/1iQwsxQ0JBUpmfaSzVIRUqNH42AdY-UWE/view?usp=drivesdk
_zPara ver el documento ingresa a Google con tu cuenta: @cicy.edu.mx
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