engleski

Different response of marrons versus naturally-growing sweet chestnut trees to Cryphonectria parasitica infection

A unique “forest/orchard” of intermixed naturally-growing chestnut trees (Castanea sativa Mill) and grafted marrons is situated in Lovran, on the northern Croatian Adriatic coast.Chestnut blight, a disease caused by an aggressive introduced fungus, Cryphonectria parasitica (Murrill) Barr, has been a problem in this area for decades, substantially reducing the number and yield of the trees. The naturally-growing chestnut populations have partially recovered due to the naturally-occurring hypovirus, which acts as a biological control agent of the fungus, but marrons still seem to succumb to the disease. A substantially higher incidence of active, expanding cankers was observed on marrons than on naturally-growing trees, although similar distribution of C. parasitica vc-types and similar incidence of associated hypovirus (CHV-1) is detected in fungal isolates from both, naturally-growing and marron trees, confirming that the lack of naturally-occurring hypovirulence or differences in fungal population are not the cause for different response of maroons to the chestnut blight. Ecological and physiological differences were ruled out since the trees are growing in close proximity and are of similar age.It seems that the marron genotype is especially vulnerable and its ability to recover is limited even when the hypovirulent strains are widespread making 60% of C. parasitica population.

biological control; Cryphonectria parasitica; genotyping; hypovirus; marron; recovery

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