Influence of application time on the establishment, survival, and ability of Clonostachys rosea to suppress Botrytis cinerea sporulation on rose debris

The influence of application time and the length of exposure to sunlight on survival, establishment, and ability of Clonostachys rosea to suppress Botrytis cinerea sporulation on rose debris were investigated in a climate-controlled greenhouse (experiment 1) and in a plastic-covered greenhouse (experiment 2). C. rosea conidia germinated significantly greater on treatments kept out of direct light for all application times. However, the germination incidence was negatively correlated with the application time for all treatments, independent of sunlight exposure. The recovery of viable conidia from leaves and the tissues colonized by C. rosea reduced exponentially as exposure to sunlight increased (from 0 to 8 h). The relative humidity (RH) was positively correlated with germination independent of sunlight exposure (r=0.95 and r=0.97, for shadow and sun, respectively). On treatments exposed to sunlight, the global radiation was negatively correlated with germination, especially during the 3 h following inoculation (r=−0.94). Despite the effects of exposure to sunlight on C. rosea, the suppression of B. cinerea sporulation was only marginally affected (suppression of 94.5–100% and 65–93%, respectively, for experiment 1 and experiment 2). These results show the ability of C. rosea to withstand adverse environmental conditions and still provide suppression of B. cinerea sporulation on rose debris.