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Poster: Diseases of Plants: Disease Detection & Diagnosis


Evaluation of molecular diagnostic methods for Monilinia species of regulatory concern
S. HAYMES (1), K. Zeller (1), Z. Abad (1), L. Knight (1) (1) USDA APHIS PPQ S&T Center for Plant Science and Technology, U.S.A.

Brown rot caused by Monilinia species is an extremely destructive disease of pome and stone fruits in many producing areas of the world, resulting in significant pre- and post-harvest losses. Diagnostics of species is difficult due to overlapping morphology, host-ranges, and symptoms. There are currently no molecular diagnostics methods that clearly discriminate all closely related species. Monilinia fructicola and M. laxa are native to or established in the US. Monilinia fructigena and M. polystroma are widely distributed in Europe and Asia and are exotic for the US. Both are listed as level “A” pests of economic importance to US agriculture in the 2015 Prioritized Offshore Pest List and the 2016 Cooperative Agricultural Pest Survey (CAPS) List. Monilinia mumecola and M. yunnanensis have been described recently (in 2004 and 2011, respectively) but are of less known impact, and neither of these species is known from the United States. The objective of this study is to evaluate two existing conventional PCR assays for distinguishing between native and exotic Monilinia for regulatory purposes. We have verified analytical sensitivity and specificity of these assays and determined the functional sensitivity with field-derived or spiked samples. A two-stage molecular diagnostic protocol that incorporates both assays allows for discrimination among all six of these Monilinia species, and should facilitate the accurate diagnosis for CAPS surveys.