[Fungal diseases of European chestnut (Castanea sativa MILL.) in Slovakia]

The work contains findings on fungal diseases of European chestnut in Slovakia coming from the own observations complemented with literature sources. Results are grouped as follows: fungal diseases of leaves, fungal diseases of stem and branches and fungal diseases of roots. The obtained results enable to consider suitability of chestnut cultivation in our condition, protection and control measures for avoding incidence and spread of infection. Till 1972 in Slovakia leaf-spot caused by fungus Mycosphaerella maculiformis (Pers.) Schroet. and its conidium stage Cylindrosporium castaneae (Lev.) belonged to the most important diseases of chestnut. On the stem and branches of chestnut except Cryphonectria parasitica (Murrill) Barr also other, less dangerous fungi occur. Out of them Cytospora intermedia Sacc., Melanconis modonia (Tul.) Hohn, Phomopsis castaneae Woronin at all chestnut localities are present. It is recomended to keep stand purity as parasitism of species from genus Cytospora Ehrenb is generaly known from literature. Although parasitism of Melanconis modonia (Tul.) Hohn was not proved it is necessary to clean the stand of stems and branches attacked with this fungus as under optimal condtion it can cause serious demages on the weakened woody species. Harmfulness of this species has been overlaped with the parasitism of fungi from genus Phytophora. [...] During 1976-1998 the health condition of European chestnut on currentlz known localities in Slovakia was evalattted concerning the incidence and spread of parasitic fungus Cryphonectria parasitica (Murrill) M.E. Barr.[...] It has been found that all isolates of Cryphonectria parasitica from the localities studied are virulent. After 96 to 120 hours of cultivation centres with pycnospores were formed on the mycelium surface. High pathogenity of mentioned fungus was proved also by artificial infection on sectioned chestnut branches and on the apple fruits of cultivar Golden Delicious. On the branches there were produced canker wounds of area 9 to 19 square mm and on apples necrotised tissue in size of 9 to 18 square mm. Virulent strains of Cryphonectria parasitica from Slovakia were tested with four hypovirulent strains coming from mycotheka of INRA in Clermont Ferrad, France. Effectiveness of treatment of cankers performed during 1992 - 1997 varied from 20.3% to 86.3%. Efficiency of hypovirulent strains has been proved in both laboratory and field conditions. [...] Out of fungi that cause injuries of chestnut leaves the most frequently occurs Mycosphaerella maculiformis (Pers.) or its conidium stage Cylindrosporium costaneae (Lev.) Krenner. It attacks leaves of seedlings, adult trees and stump sproots. The most intensively are being attacked seedlings, young trees, stump sproots and low part of tree crown. The primary infection occurs about June, 10th and first sympthoms are exhibited about June, 18 to 23rd. The own spread of the disease is as late as second half of August. Premature falling of leaves was not observed. Occationally leaves begin to fall in late September or in early October. General falling of leaves occures as late as in the beginning of November. [...] Also results obtained in biological control of chestnut blight by means of hypovirulent strains give a hope that chestnut also in our country will be preserved for future generations