Agriculture Reference
In-Depth Information
Fig 9.8 Armillaria symptoms at base of the vine when the bark is
removed.
FUNGI
ARMILLARIA ROOT ROT
■
Refer to the chapter on Common diseases of perennial fruit
crops.
BLACK SPOT (ANTHRACNOSE)
■
Cause
The fungus
Elsinoe ampelina
.
Fig 9.7 Grapevine affected by Armillaria showing yellow leaves and
poor growth.
BLACK ROT - BIOSECURITY THREAT
Cause
The fungus
Guignardia bidwellii
.
reddish-brown ring, which can grow to more than one
centimetre in diameter in one day. Within days, the
Symptoms
All young growth is susceptible, including leaves, shoots,
tendrils and berries. Tan, circular spots with a dark brown
margin, up to 10 mm in diameter, develop on leaves.
The centre of the spot dies (becomes necrotic) and
fungal fruiting bodies (pycnidia) develop as small black
pimples.
Elongated black cankers, up to 200 mm in length,
develop on young shoots during favourable conditions
throughout the season.
The initial symptom on berries is the appearance of
small, whitish dots that are rapidly surrounded by a
Fig 9.9 Black rot causes tan leaf spots and blackens bunches.
