PHYTOSANITARY CRITERIA FOR THE PROTECTION OF CHESTNUT ORCHARDS AND STANDS AGAINST CHESTNUT BLIGHT AND INK DISEASE

Chestnut trees in Europe are threatened by two serious diseases, chestnut blight and ink disease. Chestnut blight is endemic in most European countries where chestnut grows, while ink disease appears locally and irregularly. To protect chestnut orchards and stands against these diseases it is necessary to find a natural and sustainable equilibrium between the host trees and the parasites. This would improve both nut production and the ecological role that chestnut orchards play in the landscape. The management of orchards and the monitoring of stands and coppices are two ways to achieve such an equilibrium, and to find out more about the evolution of both these diseases. A correct evaluation of the health condition of trees is a necessary first step before control measures can be undertaken. Measures such as pruning and silvicultural practices for blight control encourage the spread of hypovirulent strains of the pathogen which favour the predominance of healed and healing cankers in chestnut orchards and stands. Likewise, the early diagnosis of ink disease makes it possible to apply special treatments based on adding manure that will improve both the biological activity of the soil and favour the vegetative recovery of infected trees. A management protocol based on simple and inexpensive biological control, suitable for chestnut orchards, has been developed after several years of investigations. Monitoring of the stands will detect changes in environmental conditions or the fungal populations, to which this disease management protocol can respond.