The studies on ash dying (Fraxinus excelsior L.) in the Włoszczowa Forest Unit stands

Abstract

The studies were carried out in the Włoszczowa Forest Unit, in 9 ash stands differing in respect of age, origin (natural, artificial), site and in the nursery on 3 quarters differing due to a silvicultural method (transplanted and not transplanted) and seedlings age. In each stand an analysis of disease symptoms was carried out on 100 trees (2 - 20 years old stands) or 50 trees (21 - 80 years old stands) growing side by side in central part of the stand, while in the nursery in each block 200 seedlings were analyzed (4 sectors with 50 seedlings each). From the infected seedlings and trees 120 fragments of dead branches, living branches with cankers, and dead roots were taken. Identification of fungi was made on the basis of fructification and over 300 isolations of fungi on malt agar medium. The most frequent disease symptoms in ash stands were: the dead top (34.7% trees), the dying of whole branches (83.5%), the dying of the top of branches (20.1%), the occurrence of healed (36.0%) and unhealed cankers (18.9%) and the slime flux (23.7%) on the trunk, also the chlorosis of leaves (7.5%) and their atrophy (11.2%). Most of the types of disease symptoms appeared irrespectively of the tree age, origin and site, sometimes showing only a difference in the frequency of occurrence. On the seedlings in the nursery the shoot discolouration, healed and unhealed cankers on shoots and necrosis of a part of leaves were recorded most frequently. Disease symptoms occurred more frequently on 4-year-old seedlings in comparison with 3-year-old. In respect of transplanted seedlings the leaves dying was more frequent. Within cankers and on dead tops of shoots the most frequent were: <i>Alternaria alternata</i>, <i>Chalara</i> sp., <i>Cytospora ambiens</i>, <i>Diplodia mutila</i>, <i>Fusarium lateritium</i>, <i>Gloeosporidiella turgida</i>, <i>Phomopsis controversa</i> and <i>Phomopsis scobina</i>. In sparsely found dead roots of living trees appeared mostly: <i>Cryptosporiopsis radicicola</i>, <i>Cylindrocarpon destructans</i> and <i>Phialocephala</i> sp.