Agriculture Reference
In-Depth Information
Fig 3.20
Trametes
sp. infection causes browning and papering in the
outer bark.
Pycnoporus coccineus
are up to 70 mm across, bright
orange-red in colour with a honeycomb appearance
underneath.
•
Fig 3.21
Fusicoccum
sp. fruiting bodies associated with dieback on
an apple stem.
Management
•
Schizophyllum commune
are soft, whitish brackets with
ragged edges and mushroom-like gills on the underside.
•
Prune trees carefully.
Avoid major pruning cuts. Treat necessary cuts with
the recommended wound dressing to promote rapid
healing.
•
Fusicoccum
infects limbs through pruning cuts causing
a dieback of shoots and limbs. Cankers may develop
on limbs and the tree gradually declines. Small, black
fruiting bodies of the fungus develop in the bark
on affected limbs.
•
Source of infection and spread
The fruiting bodies produced on old branches and stumps
of infected apple trees contain large numbers of spores.
Once released the wind carries them to nearby apple trees
where they germinate if conditions are suitable. The fungi
usually enter damaged tissues such as unprotected pruning
cuts and natural wounds. Once established, the fungi grow
down through the heartwood, causing dieback as infection
progresses. Limb dieback and tree decline is more common
in mature trees that have suffered stress from drought, hail,
sunscald, mechanical root damage, overcropping, poor
nutrition and severe winter pruning.
Importance
Trametes versicolor
is the most common wood-rotting
fungus affecting apple trees in Queensland.
Pycnoporus
coccineus
is a weaker pathogen but often infects newly strap-
grafted branches. Fusicoccum limb dieback is severe in
orchards affected by moisture and/or nutrient deficiencies.
Fig 3.22 Brackets of
Schizophyllum
sp. on an apple tree limb.
