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Deciphering blueberry and cranberry floral involvement in the disease cycle of Colletotrichum fioriniae
Timothy Waller: Rutgers University; Joshua Gager: Rutgers University; Peter Oudemans: Rutgers University; Thomas Gianfagna: Rutgers University
<div><i>Colletotrichum fioriniae</i> is a hemibiotrophic, fruit-rotting pathogen that limits blueberry (BB) and cranberry (CB) production. Since fungicide applications during bloom are most effective, the link between floral tissue and infection structure formation was investigated. Floral components influence both production of inoculum (secondary conidiation) and formation of infection structures (appressoria). Effects of flower tissue bioactivity on <i>C. fioriniae </i>were tested using two distinct extraction methods: water (W), to simulate mobilization of floral compounds in the field, and chloroform (C), to evaluate nonpolar cuticle compounds. W and C floral extracts significantly increased the rate (200%) and magnitude (500%) of appressorium formation and W extracts increased secondary conidiation (500%) over controls. Extracts of susceptible BB cultivars significantly increased appressorial stimulation compared to resistant cultivars, however, this was not observed in CB. Floral rainwater runoff stimulated significantly more secondary conidiation and appressorium formation compared to controls, demonstrating the presence of this phenomenon in the field. Analysis of CH extract of CB flowers and pure chemical assays showed methyl ester of hexadecanoic acid (HEX) as the most stimulatory compound characterized. Utilizing this, HEX was field-tested with fungicides as a ‘trap’ spray, synchronizing fungal germination to fungicide applications with moderate early season control.</div>

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