Dothistroma needle blight Mycosphaerella pini E. Rostrup and its anamorphic stage Dothistroma septospora (Dorog.) Morelet was detected for the first time in the territory of the Czech Republic in a consignment of imported plants of Austrian pine Pinus nigra Arnold in 1999. In 2000, it was also found on Pinus nigra in an open planting in a plantation of Christmas trees by the village of Jedovnice near Brno in South Moravia. In the Czech Republic, Dothistroma needle blight was identified on 13 species of pine. Pinus nigra Arnold and Pinus mugo Turra are the most frequent hosts. In addition to these species, Dothistroma needle blight was observed on Pinus ponderosa Douglas ex Lawson, Pinus jeffreyi Grev. et Balf, Pinus banksiana Lamb., Pinus contorta Douglas, Pinus rotundata Link, Pinus leucodermis Ant. and Pinus sylvestris L. Finds on Pinus aristata Engelm., Pinus rigida Mill., Pinus heldreichii H. Christ. and Pinus cembra L. var. sibirica (Du Tour) G. Don. are a certain rarity. These species are not mentioned anywhere as potential hosts of Dothistroma needle blight. As for the species of other genera Picea pungens Engelm., Picea abies L. Karst. and last but not least Picea schrenkiana Fisch. & C. A. Mey were also observed as hosts. The host range of Dothistroma needle blight recorded in papers is noted as well.

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. banksiana Lamb., P. contorta Loudon, P. mugo Turra, P. leucodermis Ant., P. sylvestris L., P. cembra L., P. aristata Engelm., P. ponderosa P. et C. Lawson and P. jeffreyi Grev. et Balf.). Also Picea pungens 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 2-4 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.

This chapter focuses on foliar diseases of conifers, pines, spruces, firs, larches, yews and Cupressaceae. Information is given on their detection, infection biology, epidemiology, and management strategies and tactics.

Dothistroma needle blight Mycosphaerella pini is an important pathogen of pine needles. In addition to different species of pine, M. pini was found in blue spruce Picea pungens in the proximity of infected Pinus nigra in the region of southern Moravia about 20 km SE of Brno. KARADŽIĆ (1994) reported the occurrence of Dothistroma needle blight in spruce Picea omorica and Douglas fir Pseudotsuga menziesii in the region of Serbia. As for Norway spruce Picea excelsa, M. pini was detected in 6-year-old plants in Bavaria (LANG 1987). Keywords CONCLUSIONDothistroma needle blight is the most important forest quarantine disease spreading in the Czech Republic. The present spectrum of hosts includes virtually all species of pine. The described infection of Picea pungens appears to be the result of high infection pressure in the proximity of an affected tree in combination with unsuitable site conditions. The infection of blue spruce Picea pungens by Dothistroma needle blight is an exception and, for the present, it is not a case of mass adaptation to a new species.R e f e r e n c e s

The population of microorganisms in wheat rhizosphere changed in the presence of the fungus Gaeumannomyces graminis var. tritici causing the take-all of wheat. In the majority of cases when the soil was artificially contaminated by the fungus, both the number of bacteria in the rhizosphere and the bacteria/fungi ratio temporarily increased. At the beginning bacteria growing in the presence of NH4+ predominated, later bacteria utilizing organic N-substances prevailed. Pseudomonas fluorescens and the related species colonized the rhizosphere and the soil to a greater extent in the presence of G. graminis. The wheat rhizosphere with G. graminis was found to contain a higher level of the slime-producing bacterium Agrobacterium spp.; this microorganism occurred on hyphal surfaces (in hyphosphere) of both G. graminis growing in soil and Mucor spp. Changes in microbial populations in the wheat rhizosphere during the first stage of colonization by G. graminis can be partly explained by a simultaneous rhizosphere colonization by microorganisms which accompany this fungus in soil. In the period of increase in the number of bacteria in rhizosphere a temporary stimulation of wheat growth was observed.