Infectious diseases in forest trees caused by viruses, mycoplasma-like organisms and primitive bacteria

Virus contamination of soils in forest ecosystems of the Federal Republic of Germany

“…Forest decline in European countries is understood to be a complex interaction of biotic and abiotic factors. These interchangeable factors of predisposing, inciting and contributing categories were first described by MANION (1981) in a decline disease spiral which was modified by NIENHAUS (1985) in respect to viruses and primitive prokaryotes. These pathogens are widespread in wild plants and agricultural crops.…”

“…Tobamoviruses could be rarely isolated from forest soils, although strains of tobacco mosaic virus were formerly found in leaf samples of a number of oak trees in the Rhineland area (NIENHAUS 1975). TMV-like particles are also reported in oaks growing in East-Germany (ScHMELZER et al 1966) and Hungary (HORVATH et al 1975).…”

Endophytische Pilze in Blättern und Ästen gesunder und geschädigter Buchen (Fagus sylvatica L.)

“…der Rhizosphaere, Fehler im Waldbau und Veranderungen des Klimas genannt (BOR-MANN 1985;LiCHTENTHALER und BuscHMANN 1984;MANION 1985;SCHUTT et al 1985;SCHUTT 1985;WARGO 1985). Nach anderen Autoren konnten auch Viren, Bakterien (Mykoplasmen) und Pilze eine wichtige Rolle spielen (GECH et al 1961;NIENHAUS 1985;REHFUESS und RODENKIRCHEN 1984). Tatsachhch ist es heute aufierordentlich schwierig, Krankheitsbilder zu unterscheiden, die im einen Fall durch ein Pathogen und im anderen durch abiotische Faktoren verursacht wurden.…”

Detection of mycoplasmalike organisms in declining oaks by polymerase chain reaction

“…Despite multidisciplinary efforts to elucidate the cause(s) of this ecologically and economically important problem, the etiology of oak decline is still not fully understood. Several biotic and abiotic factors such as parasitic fungi that attack bark and cambium of stems and roots, defoliation by insects, virus infections, water stress, winter frost, and air pollution are thought to be involved (BLANK and HARTMANN 1993;DELATOUR 1983;KEHR and WULF 1993;KRAPEENBAUER 1987;NIENHAUS 1985). However, none of these factors appears to be the sole cause of this problem.…”