デイゴ南根腐病の発生実態

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The appearance of symptoms and signs on the upper and lower parts of infected trees and infection of pathogenic fungi by mycelium were researched on the brown root rot of Erythrina variegate var. orientalis caused by Phellinus noxius. It was observed that the lower part of infected trees began to die earlier than the upper part and the lower part had died completely during the stage when defoliation and withering of branch tips were occurring in the upper part. The first symptom appeared in the upper part was yellowing when the lower part began to die. This was followed in succession by defoliation, withering of branch tips, death of branches and upward expansion of death in the stem base as dead areas in the lower part of an infected tree spread, eventually resulting in the death of the entire tree. In the investigation of trees that showed yellowing of leaves in the upper part, infection was observed to have expanded to the root and butt after the pathogen was introduced by mycelium from a neighboring diseased tree through root-to-root contact. It was concluded that it takes about two years for a tree to completely die after initial pathogenic infection by a neighboring diseased tree.デイゴ南根腐病について, 地上部と地下部の病徴および標徴の現れ方, および菌糸体により病原菌が伝染している状況を明らかにした｡地上部と地下部の枯死時期には時間的にずれがあり, 地下部のほうが地上部よりも先に枯死が進行し, 地上部に落葉や枝先枯れが発生している段階で地下部の全部が枯死している｡地下部の枯死の進行に伴って地上部に現れる病徴は, 初めは葉の黄化だけで, 地下部の枯死が広がるに連れて葉枯れと落葉, 枝先枯れ, 枝の枯れ下がり, 地際上部への主幹の枯死などが順次加わり, 最後は全身枯死へと至る｡地上部に葉の黄化を現す調査木において, 病原菌が菌糸体により隣接木から根と根の接触を介して伝染した後に, 根系と根株に伝染を広げている状況が観察された｡隣接する罹病木から病原菌が伝染した後に全身枯死に至るまでの期間は約２年を要した｡
2010-03-01

デイゴ南根腐病の発生実態

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