Open flowers and concentrated bloom periods are critical times for fruit rot control in blueberries and cranberries as well as several other horticultural crops. It is reasonable to hypothesize that plant signals produced during bloom play a critical role in the infection processes of, at least, some fruit rotting fungi. In this project, we investigate the effects of water-soluble flower extracts (FE) on the development of disease in the fruit rotting fungi <i>Coleophoma empetri, Colletotrichum acutatum </i>and <i>Colletotrichum gloeosporioides</i>. Conidial suspensions treated with FE demonstrated increased appressorium formation <i>in vitro</i> as well as increased virulence on detached fruit. A comparison of FE derived from susceptible and resistant cultivars of blueberry suggests a significant difference in the rate of appressorium formation that correlates with field resistance<i>. </i>Time course experiments show that inclusion of FE in an infection droplet can significantly increase the rate of spore germination and appressorium formation. Therefore, FE may provide a key stimulus that reduces the minimum wetness period needed to initiate infection. Given these data, we hypothesize that FE are a viable target for disease control and trials aimed at evaluating bacteria to offset the stimuli of FE and reduce disease incidence are underway.
