Effects of various densities of Ophiostoma ips inoculations on Pinus sylvestris in north‐western Spain
The aim was to determine the inoculation density above which Scots pine (Pinus sylvestris) is overcome by the blue‐stain fungus Ophiostoma ips that is associated with the bark beetle Ips sexdentatus. In north‐western Spain, stems of 16 Scots pines
were inoculated at various densities (0, 400, 800 or 1600 inoculi/m2) along circumferential 100 or 150 cm wide inoculation belts. Each inoculum consisted of a 5 mm diameter cylinder of malt extract agar colonized by the fungus. Three months later, all trees were harvested
and trunk resinosis and foliage colour were visually assessed. The percentage of healthy, desiccated, resin soaked, and blue‐stained sapwood, as well as growth productivity indices, were calculated from stem disks cut from within the inoculated zone of each tree. Sapwood‐specific
hydraulic conductivity (Ks) of each tree was measured in the middle of the inoculated zone. All parameters of tree vigour changed dramatically to the worse when inoculation densities were above 400 inoculi/m2, and foliage changed from green to yellow‐green or yellow
when an inoculation density of 800 instead of 400 was used. The percentage loss of sapwood‐specific conductivity (PLC) increased from 30 to 90% and the percentage of healthy, conductive sapwood dropped from 85 to 35% at 800 inoculi/m2. No effect of the width of the inoculation
belt was observed, and there was no relationship between tree productivity indices and the level of resistance. A non‐linear negative relationship was found between PLC and the percentage of healthy sapwood. It is concluded that tree resistance was overcome and that trees were going
to die when the inoculation density was ≥800 inoculi/m2.
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Document Type: Research Article
Área de Zoología, Dpto. Ciencias Agroforestales, E.T.S.I.I.A.A. de Palencia, Universidad de Valladolid, Spain.
Área de Fisiología Vegetal, Dpto. Biología Vegetal, Fac. C.C. Biológicas y Ambientales, Universidad de León, León, Spain
Laboratoire de Biologie des Ligneux et des Grandes Cultures, Université d’ Orléans, BP 6759, 45067 Orleans Cedex 2, France
Publication date: 2004-08-01