Biological Control of the Chestnut Blight Canker, Experience from Albania

Field surveys in chestnut stands in Albania have emphasized a widespread presence of chestnut blight in the plots studied caused by C. parasitica. After the severe damage caused by blight, a spontaneous re-growing of chestnut trees has been observed in relation to the natural spread of hypovirulence, which is caused by the hypovirulent strains of C. parasitica, the causal agent of blight. Observations have highlighted the effectiveness of the natural spread of hypovirulence, with a clear prevalence of healed and healing cankers, in almost all of the stands surveyed. Inocula produced in healing cankers collected in the study sites were investigated by means of laboratory and field tests. Differing percentages of C. parasitica morphotypes (normal, intermediate, white) were detected. At all sites diversity of the vegetative compatibility (vc) of C. parasitica is present and the results for vc groups detected from the Albanian isolates of C. parasitica. Inoculations using these inocula produced healing cankers, while strains obtained from single conidia isolations produced different infections and cankers. Biological control by field inoculation using the hypovirulent strains into virulent cankers and into canker free (healthy trees) on chestnut tree yielded excellent. The use of natural and biological controls makes it possible to limit the damage caused to chestnut trees by this disease.