|Red light stimulates apothecial development of Monilinia vaccinii-corymbosi|
J. FLORENCE (1), J. W. Pscheidt (1). (1) Oregon State University, Corvallis, OR, U.S.A.
Pseudosclerotia of<i> Monilinia vaccinii-corymbosi,</i> the fungus that causes mummy berry disease of blueberry, overwinter on the soil surface producing apothecia in early spring. Although light is necessary, it is unknown what quality or intensity is needed for apothecium development. Pseudosclerotia, collected from beneath bushes of cv. ‘Berkeley’ in Corvallis, OR, were placed on 10 g of sterile sand inside black painted polyethylene scintillator vials and watered. Vials were capped with a clear, red, or blue light filter, placed into one of two photosynthetrons in a completely randomized design, and incubated at 9-10°C. Photosynthetrons were positioned 60 cm from two compact fluorescent bulbs on a 12-hr photoperiod with 2.1 μmol/m<sup>2</sup>/s intensity. Pseudosclerotia were monitored for 14 days for apothecia development. The mean proportion of apothecia for the blue filtered light treatment, averaged across 3 trials, was 0.27 (standard deviation [SD] = 0.46), while the mean proportion of apothecia for clear and red filtered light were 0.45 (SD =0.51) and 0.41 (SD = 0.50), respectively. The blue filtered light treatment had the lowest mean but was not statically significant. An increase in sample size by combining the results from 2014 and current 2015 trials may provide enough power to detect a significant difference. Results may help determine depth of mulch used to inhibit apothecial emergence.