Dothistroma needle blight Mycosphaerella pini E. Rostrup, a new quarantine pathogen of pines in the CR

Abstract

Dothistroma needle blight caused by Mycosphaerella pini E. Rostrup was observed for the first time in the Czech Republic on an imported Pinus nigra Arnold in 1999. In 2000, it was also found in the open planting. During three years, it became an important pathogen of pines in the Czech Republic. Its occurrence was noticed in more than 50 localities, above all in the region of Moravia and Silesia and eastern Bohemia. In total, it was found on 10 species of pine (P. nigra Arnold, P.&nbsp;banksiana Lamb., <br />P. contorta Loudon, P. mugo Turra, P.&nbsp;leucodermis Ant., P. sylvestris L., P. cembra L., P. aristata Engelm., P.&nbsp;ponderosa P. et C.&nbsp;Lawson and P. jeffreyi Grev. et Balf.). Also Picea pungens &nbsp;Engelm. was noticed as a host species. In the Czech Republic, Pinus nigra is the most frequent host species of M. pini (80% localities) followed by Pinus mugo (27% localities). On Scots pine P. sylvestris, M. pini was noticed at two localities. The critical period for infection is in the Czech Republic from the second half of May until the end of June. The incubation period lasts about 2&ndash;4 months depending on climatic conditions. The first symptoms on the needles infected in the current year appear in August being clearly expressed from September to November.In the CR, Dothistroma needle blight spread probably with infected planting stock obtained from import at the end of the 80s and at the beginning of the 90s.