Latent Infection of Valsa mali in the Seeds, Seedlings and Twigs of Crabapple and Apple Trees is a Potential Inoculum Source of Valsa Canker.

A real-time quantitative PCR assay using a species-specific primer pair was developed to rapidly and accurately quantify Valsa mali, the causative pathogen of apple Valsa canker (AVC), in crabapple seeds, crabapple seedlings, apple twigs and apple seeds. Surveys were conducted in different regions, and crabapple or apple seeds were collected for V. mali detection by qPCR assay.