Presentation Type

Proceeding Paper

Publication Date

8-13-2018

Subject Category

Blueberry Pathogens (fungi, bacteria, viruses and others)

Description

Monilinia vaccinii-corymbosi (Reade) Honey (M.vc), the causal agent of Monilinia blight of wild blueberry, is controlled primarily by fungicide applications. Demethylation-inhibiting fungicides (DMIs) have been used for over 30 years for Monilinia blight control due to flexibility of use (i.e., ability to use after an infection period) and disease control effectiveness and consistency. In the present study, the sensitivity of ten M.vc isolates to three DMIs- propiconazole, difenoconazole and prothioconazole-desthio were evaluated in vitro by a mycelial growth inhibition assay. In addition, four field trials were conducted during two crop seasons: 2012 and 2013, to examine the efficacy of these DMIs to control Monilinia blight. All the tested DMIs were effective in inhibiting mycelial growth of M.vc isolates, although the mean EC50 values differed significantly. In field experiments, three of four trials had significant treatment effect on disease incidence and severity of vegetative buds. Prothioconazole-desthio and propiconazole provided consistent control against Monilinia blight. Conversely, difenoconazole was effective in in vitro analysis, but did not demonstrate satisfactory Monilinia blight control in all field trials. In the 2012 trials, both prothioconazole-desthio and propiconazole reduced disease incidence of vegetative buds by 100% compared to the untreated control. Prothioconazole- desthio reduced disease development in 2013 with 94 and 99.8% less incidence, and 75 and 99.5% less severity. Similarly, propiconazole also reduced incidence of vegetative buds by 88% and 99.8%, and severity by 54% and 99.7%. No phytotoxic symptoms were observed in any of the field trials. The results of the study serve as a benchmark to monitor shifts in M.vc sensitivity to these fungicides in the future.

Start Date

13-8-2018 5:15 PM

End Date

13-8-2018 5:30 PM

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Aug 13th, 5:15 PM Aug 13th, 5:30 PM

Monilinia vaccinii-corymbosi sensitivity to demethylation inhibitor fungicides and its effect on Monilinia blight control in wild blueberry fields

Monilinia vaccinii-corymbosi (Reade) Honey (M.vc), the causal agent of Monilinia blight of wild blueberry, is controlled primarily by fungicide applications. Demethylation-inhibiting fungicides (DMIs) have been used for over 30 years for Monilinia blight control due to flexibility of use (i.e., ability to use after an infection period) and disease control effectiveness and consistency. In the present study, the sensitivity of ten M.vc isolates to three DMIs- propiconazole, difenoconazole and prothioconazole-desthio were evaluated in vitro by a mycelial growth inhibition assay. In addition, four field trials were conducted during two crop seasons: 2012 and 2013, to examine the efficacy of these DMIs to control Monilinia blight. All the tested DMIs were effective in inhibiting mycelial growth of M.vc isolates, although the mean EC50 values differed significantly. In field experiments, three of four trials had significant treatment effect on disease incidence and severity of vegetative buds. Prothioconazole-desthio and propiconazole provided consistent control against Monilinia blight. Conversely, difenoconazole was effective in in vitro analysis, but did not demonstrate satisfactory Monilinia blight control in all field trials. In the 2012 trials, both prothioconazole-desthio and propiconazole reduced disease incidence of vegetative buds by 100% compared to the untreated control. Prothioconazole- desthio reduced disease development in 2013 with 94 and 99.8% less incidence, and 75 and 99.5% less severity. Similarly, propiconazole also reduced incidence of vegetative buds by 88% and 99.8%, and severity by 54% and 99.7%. No phytotoxic symptoms were observed in any of the field trials. The results of the study serve as a benchmark to monitor shifts in M.vc sensitivity to these fungicides in the future.