Effects of diseases on chestnut orchards and forest ecosystems

Abstract

Chestnut blight and ink disease, the two most destructive diseases of chestnut (Castanea sativa Miller), are spreading through European chestnut orchards and stands, playing an important role in their evolution and affecting management. Predominance of hypovirulence was observed in the majority of European countries. Abnormal cankers arising from the action of hypovirulent strains of Cryphonectria parasitica were detected in the stands investigated. Blight may be now considered as naturalised and endemic in almost all European chestnut stands but, because of the spread of hypovirulence, damage primarily affects weak and stressed trees. Blight can act as a bio-regulator in chestnut ecosystems. Spread of new virulent lines of the parasite, wildfire and other stress factors can change this favourable situation, but in the chestnut stands visited to date this occurs in limited areas and only for a short time. Sylvicultural management and, if necessary, artificial combined inoculation with selected hypovirulent strains enhances natural biological control of the disease. Ink disease attacks produce severe damage in chestnut stands and influence their evolution towards mixed woods. Monitoring of ink disease foci and control of blight evolution are desirable in chestnut management projects.