Effects of the plant-pathogenic fungus Mycocentrospora acerina (Hartig) Deighton on growth and competition of Viola arvensis (Murr.) in spring wheat

Mycocentrospora acerina (Hartig) Deighton can kill or suppress the growth o f Viola arvensis (Murr.) in spying wheat in pot-grown plants in both glassh ouse and outdoor studies. The level of damage to V arvensis and the effect on its competition with wheat were affected by inoculum density and environ mental conditions. High inoculum density (10(5) macroconidia/ml) caused hig h mortality in V. arvensis and eliminated its competitive effect on wheat. At a lower density (10(4) macroconidia/ml), the V. arvensis fresh weight an d its competition with the wheat were suppressed by up to 38 and 28% respec tively, depending on environmental conditions.