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Báo cáo khoa học: "Scots pine susceptibility to attack by Tomicus piniperda (L) as related to pruning date and attack density"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: "Scots pine susceptibility to attack by Tomicus piniperda (L) as related to pruning date and attack density. | AnnSciFor 1993 50 101-117 Elsevier INRA 101 Original article Scots pine susceptibility to attack by Tomicus piniperda L as related to pruning date and attack density B Lảngstrõm c Hellqvist Swedish University of Agricultural Sciences Division of Forest Entomology S-776 98 Garpenberg Sweden Received 25 May 1992 accepted 23 November 1992 Summary The susceptibility of young Scots pine to bark beetle attack was increased by pruning trees to a similar crown size 10 7 and 1 month s prior to beetle flight. Beetle population in the study area was high and spontaneous attacks were expected to occur on the pruned trees. Half of the trees were baited with split pine bolts in order to attract more beetles to attack these trees. Thus experimental trees carrying one-third of their original foliage and with different vigour indices due to the pruning history were exposed to 2 levels of beetle attack. The pine shoot beetles preferentially attacked baited trees whereas attack rates did not differ between pruning dates. Six wk after attack beetle performance was better in trees pruned shortly before attack than in trees pruned earlier. Vigour indices differed between the 2 treatments but phloem starch secondary resinosis expressed as lesion size and resin acid content and tree survival did not. Trees that eventually survived were significantly less attacked than those that died but the 2 groups did not differ in tree characteristics except in cambial electrical resistance . pine shoot beetles Pinus sylvestris I beetle performance defence reactions host vitality Resume Susceptibilité du pin Sylvestre aux attaques de Tomicus piniperda L en fonction de la date d elagage et de la densité d attaque. La susceptibilité dejeunes pins Sylvestre aux atta-ques de scolytides a été accrue en élagant les arbres de fagon á ce que la taille de leur couronne soit comparable. Les élagages ont eu lieu environ 10 7 et 1 mois avant le vol des insectes. Les ni-veaux de population dans la zone d etude .