TAILIEUCHUNG - Báo cáo lâm nghiệp: " Scots pine responses to number and density of inoculation points with Leptographium wingfieldii Morelet, a bark beetle-associated fungus"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Scots pine responses to number and density of inoculation points with Leptographium wingfieldii Morelet, a bark beetle-associated fungus. | 497 Ann. Sci. For. 55 1998 497-506 Inra Elsevier Paris Note Scots pine responses to number and density of inoculation points with Leptographium wingfieldii Morelet a bark beetle-associated fungus Luc Croiséa b Franẹois Lieutierb Erwin Dreyera a Unite écophysiologie forestiere Inra Centre de Nancy 54280 Champenoux France b Station de zoologie forestiere Inra Centre d Orleans 45160 Ardon France Received 8 April 1997 accepted 21 August 1997 Abstract - The effects of different densities and total distribution of inoculation points with Leptographium wingfieldii a fungus associated with the bark beetle Tomicus piniperda were investigated in Scots pine Pinus sylvestris . During April 1993 40 8-year-old Scots pine trees were inoculated into the trunk and until the cambium at breast height. Inoculation points were distributed over a circular belt of 20 40 70 and 100 cm width at two densities 200 and 400 nr2 . Three months after inoculation the average length of the induced reaction zone was recorded on the external side of the phloem. The fraction of sapwood section that appeared blue-stained desiccated or soaked with resin was also measured. The length of the visible induced reaction zone in the phloem was affected neither by inoculation density nor by width of the inoculation belt. Similarly the fraction area of damaged sapwood was small and constant at 200 m 2. It increased significantly only at the highest density 400 nr2 as a function of belt width reaching 70 at 100-cm width. It is concluded that i the average length of the induced reaction zone in the phloem is insensitive to inoculation density and ii the importance of damage in the sapwood is increasing only at inoculation densities above 400 m 2 over a sufficiently large area. This result is discussed in relation to the physiological meaning of the different symptoms and in relation to the concept of threshold of attack density to explain why pine trees are affected only when the density of bark beetle attacks .

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