Agriculture Reference
In-Depth Information
Importance
Leaf mould is a common disease in most olive production
regions and often occurs in combination with peacock spot.
Importance
Peacock spot is a common and widespread leaf disease
of olive. It is most common and serious during wet spring
weather and is inactive during the hot summer months.
Severe infections can result in defoliation, causing death
of new wood and reduced yields in the following year.
Management
•
Prune trees to open the canopy and improve airfl ow
to reduce humidity levels.
Management
•
Avoid over-fertilising, particularly with nitrogen.
•
The management methods outlined for leaf mould also
apply to peacock spot.
Avoid excessive irrigation, which raises humidity levels
and maintains leaf wetness if overhead sprinklers are used.
•
Apply protectant copper sprays in early spring.
•
PHYTOPHTHORA ROOT ROT
■
PEACOCK SPOT (OLIVE LEAF SPOT,
BIRD'S EYE SPOT)
Cause
The oomycete
Phytophthora
(several species).
■
Cause
The fungus
Fusicladium oleagineum
.
Symptoms
Root and crown cankers develop and may extend up the
trunk. Leaves yellow, wilt and may fall from the plant.
Symptoms
Round spots, 2-10 mm in diameter, develop on the upper
surface of the leaf and occasionally on the stems and fruit.
Spots first appear as small, pale blotches, later becoming
muddy green to black and often surrounded by a yellow
halo. Spots on the underside of the leaf are grey.
Young leaves may be symptomless.
Source of infection and spread
Spores are spread by water splash and wind during humid
or wet weather.
The fungus overwinters in old infected leaf material.
Fig 13.8 Peacock spot. Round spots develop on the upper surface
of leaves.
Fig 13.9 Phytophthora symptoms on an olive stem.
