Zdrowotność topoli na plantacjach w strefach ochronnych hut miedzi Legnica i Głogów

The health status of 6−16−year−old poplars (mostly Populus robusta) in the sanitary protection zones around Legnica and Głogów copper mills (SW Poland) is described. The health of the poplars was assessed as a frequency of trees with symptoms of stem canker and occurrence of virus diseases on leaves. Fungi were isolated from 24 samples of canker wood (20×20×20 cm each) in five afforested complexes and then identified on the basis of colony morphology and sporulation on PDA and SNA after 40 days of incubation. Cankers occurred on <5−95% of poplar trees. Poplar mosaic virus was observed sporadically in collections of P. robusta, P. balsamifera and P. gerlica. The canker wood was colonized by 20 species of facultative pathogens. Acremonium pteridii, Exophiala sp. and Gibberella baccata were the most common and frequent (in 4−5 complexes). Aureobasidium pullulans, Epicoccum nigrum and Fusarium solani occurred in 3−4 complexes. Alternaria alternata, Cadophora fastigiata, Didymella molleriana, Fusicolla aquaeductuum, Gibberella avenacea, Graphium sp., Leptosphaeria maculans, Nectria inventa, Phoma herbarum, P. minutella, Sarocladium strictum, Trichosporon ovoides and Valsa sordida were less frequent and often occurred only locally. The fungi recorded may serve as indicators of the vitality and health status of trees in industrial zones. The best approach to eliminate the risk of colonization by pathogens is to maintain trees in a state of vigorous growth. Management practices that promote good growth include fertiliza− tion, watering during drought, avoidance of unnecessary wounding of trunk and roots, and using correct pruning procedures.