Efficacy, persistence and residue levels of fungicides for Botrytis control in wild blueberry

Abstract

Botrytis blossom blight disease is one of the major challenges to wild blueberry production with annual losses frequently exceeding 20%. In this study, the effect of different fungicide treatments on Botrytis blight development and yield, as well as the mobility and persistence of these fungicides within flower tissues, and fruit of wild blueberries were evaluated under field conditions. This multi-year trial examined five different fungicides (Switch®, Luna Tranquility®, Merivon® Xenium, Propulse®, and Miravis® Prime) each one applied twice at 7-10-day interval. Fungicide quantification in the floral and berry tissues was conducted using a modification of the QuEChErs extraction method and analyzed with GC-MS and HPLC-MS. All the treatments except Switch® reduced disease incidence by over 78 % and severity by over 40 %, compared to the control plots. Switch® and Miravis® Prime reduced both incidence and severity by over 64 % compared to the control plots. Luna Tranquility®, Merivon® Xenium, and Propulse® reduced incidence by at least 47 % and severity by 51 % compared to the control plots. Berry yields were higher in Switch®, Luna Tranquility® and Miravis® Prime treated plots with at least a 19% increase in yield compared to the control plots. The mean concentration of all quantified fungicides was higher in the corolla compared to the gynoecium and the androecium sample areas. Fungicides were persistent and concentrations were sufficient to suppress Botrytis cinerea at fruit set (10 days post application) with no residue detected in harvested berries, except prothioconazole-desthio.