At present, the parasitic fungus Cryphonectria parasitica appears to be the main problem in the spread of the chestnut population. Its spores spread in the wind, rendering most of the preventive measures against this infection ineffective. Treatment of infected trees is possible through the application of hypovirulent ( that means non-virulent ) strains of the same fungus, but practical implementation poses problems related to the accessibility of the protective agent.
A simpler solution is to spread chestnut varieties that, even after infection by the fungus, create their own defense mechanism and do not give up without a fight like our traditional varieties of Castanea sativa. We are talking here about the hybrid varieties obtained by selecting hybrid seedlings that arose from free pollination of the Japanese chestnut (Castanea crenata) and the European chestnut (Castanea sativa). The hybrid varieties MARSOL, MARAVAL, MARIGOULE and BOUCHE de BÉTIZAC present a French way of solving the disease problem in edible chestnuts.
