Colletotrichum fioriniae Development in Water and Chloroform-based Blueberry and Cranberry Floral Extracts.

Abstract

To accurately monitor the phenology of the bloom period and the temporal dynamics of floral chemical cues on fungal fruit rotting pathogens, floral extraction methods and coverslip bioassays were developed utilizing Colletotrichum fioriniae. In blueberry and cranberry, this pathogen is optimally controlled by applying fungicides during the bloom period because of the role flowers play in the initial stages of infection. The protocol detailed here describes how floral extracts (FE) were obtained using water-, chloroform-, and field rainwater-based methods for later use in corresponding glass coverslip bioassays. Each FE served to provide a different set of information: response of C. fioriniae to mobilized floral chemical cues in water (water-based), pathogen response to flower and fruit surface waxes (chloroform-based), and field-based monitoring of collected floral rainwater, moving in vitro observations to an agricultural setting. The FE is broadly described as either water- or chloroform-based, with an appropriate bioassay described to compensate for the inherent differences between these two materials. Rainwater that had run off flowers was collected in unique devices for each crop, alluding to the flexibility and application of this approach for other crop systems. The bioassays are quick, inexpensive, simple, and provide the ability to generate spatiotemporal and site-specific information about the presence of stimulatory floral compounds from various sources. This information will ultimately better inform disease management strategies, as FE decrease the time needed for infection to occur, thus providing insight into changing risks for pathogen infection over the growing season.