Spread of chestnut blight in a plantation of young Castanea sativa and Castanea hybrids.

摘要

The study was carried out in a plantation of young Castanea sativa Mill. and Castanea hybrids established in 1998 near the village Pribelce. At the beginning of the study in 2003, the trees in the plantation were represented by 155 seedlings derived from open pollination of both F1 progeny of C. sativa x C. crenata and C. sativa x C. sativa crosses and C. sativa old trees and by grafts collected from F1 progeny of the mentioned crosses and from C. sativa old trees grown on different locations in Slovakia. During five consecutive years, from 2003 to 2007, annual increasing infestation of chestnut accessions by Cryphonectria parasitica were recorded. An old European chestnut tree, that grew close to the accession collection, damaged by chestnut blight in 2002, was considered as initial focus of disease dispersal. In isolates collected from these trees and also in isolates from all young cankered accessions a single vc type of C. parasitica, compatible with EU-12, was detected. Disease incidence was the highest around the initial focus (within a radius of 140 m) and decreased with the progressive distances from this focus. The disease spread prevailed downslope in congruent direction with the second most frequent wind direction, which was however of the highest speed. The number of newly cankered accessions positively correlated with the ambient air temperature, namely with average daily minimal air temperatures for period January-July of the surveyed year. Proportion of cankered accessions among seedlings (24, 27 and 8%) and grafts (29, 23, 30%) of different origin did not differ significantly. In spite of this some differences in susceptibility to chestnut blight were observed in seedlings derived from different C. sativa x C. crenata crosses.