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International
Congress Rhizosphere, Munich 2004
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3488 |
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Pathogenicity and competence of armillaria species for infecting
pinus plants.
Aguín O¹, Sainz
MJ², Mansilla JP¹²
1 Estación
Fitopatolóxica do Areeiro, Excma. Diputación Provincial de
Pontevedra, Subida a la Robleda s/n, 36153 Pontevedra, España.
2
Departamento de Producción Vegetal, Universidad de Santiago de
Compostela, Campus Universitario, 27002 Lugo, España.
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ABSTRACT: White root rot in
Pinus sp. is mostly caused by Armillaria ostoyae, and in some
cases by A. mellea. Armillaria gallica has also been reported
infecting Pinus plants, although it is considered a weak parasite. A growth
chamber experiment was carried out to study the pathogenicity of A.
mellea, A. ostoyae and A. gallica and their competence in the
rhizosphere for infecting plants of Pinus radiata and Pinus
pinaster. Surface-disinfected seeds were seeded in 150 mL pots containing a
sterile mixture of pine bark, peat and perlite. After six months, healthy
well-developed plants were transplanted to 500 mL pots with the same substrate
(one plant per pot), and allowed to grow for three months. Then inoculation
treatments with each single fungus, and combined treatments with two or three
of them, were established, as well as the corresponding uninoculated control,
for each Pinus species. Inoculum of Armillaria consisted in 2.5 x
1 cm hazel rods, completely covered by mycelium and rhizomorphs, that were
inserted close to roots in each pot. Uninoculated rods were placed in control
and single or dual inoculated pots. There were 10 replicates per treatment.
After four months growth, fresh and dry weights of roots, shoots and fungal
rhizomorphs in soil were recorded in five replicates. Samples of rhizomorphs
were also taken to identify Armillaria species by PCR-RFLP methods. Dual
inoculation of A. ostoyae and A. gallica significantly decreased
shoot dry weight of both Pinus species; however, when these two fungi
were separately inoculated, no differences were found respect to the
uninoculated control. In P. pinaster, root growth was significantly
reduced when A. mellea and/or A. ostoyae were inoculated. It
could be observed that the amount of rhizomorphs produced by A. gallica
increased significantly when this fungus was simultaneously inoculated with
A. ostoyae and/or A. mellea.
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