Agriculture Reference
In-Depth Information
Maintain hygiene in the packing shed, cleaning
equipment regularly with disinfectant and removing
waste fruit daily.
•
Use the recommended postharvest fungicide treatment.
•
DIEBACK
■
Cause
The wood-rotting bracket fungi
Trametes versicolor
('Polystictus'),
Schizophyllum commune
(yellow heart rot),
Tra m e t e s ve l u t i n a
,
Pycnoporus coccineus
,
Stereum
strigosozonatum
and
Stereum purpureum
.
Fig 17.14 Severe postharvest loss caused by brown rot in peaches.
Symptoms
At first, the outer bark of affected branches browns and
develops a papery appearance. These branches rapidly lose
vigour and die. Fungal brackets (fruiting bodies) can
develop on the diseased wood. Some characteristics of the
brackets are described below:
increases rapidly after any insect injuries, wind and hail
damage, or bruising. Postharvest contamination of fruit
with brown rot spores may occur during handling and
packing, resulting in infection and extensive breakdown
in transit and storage.
Importance
Brown rot is the most important disease of stone fruit in
Australia. The disease is particularly serious and difficult to
control in wet seasons. Brown rot caused by
M. fructicola
mainly infects peaches and nectarines. Serious losses can
occur both before and after harvest. Brown rot caused by
M. laxa
is mainly a disease of blossom, especially after cold,
wet conditions, and is most serious in apricots and plums.
Management
•
Spray trees thoroughly with recommended fungicides
during blossoming and the month before harvesting. An
additional fungicide spray during dormancy is also
needed if stone fruit have been affected by blossom blight.
Adopt a strategy to avoid brown rot resistance to
fungicides. This strategy is not to rely on one fungicide
group but to alternate between fungicide groups.
•
Prune and shape trees to ensure thorough application
of fungicides.
•
Manage insect pests that cause fruit surface injury,
because they can spread the disease.
•
Prune out and destroy all diseased twigs and 'mummies'
during winter. Continue to remove infected fruit and
mummies from trees and the orchard fl oor during the
season. Dispose of infected plant parts well away from
the orchard.
•
Fig 17.15 Brackets of the fungus
Schizophyllum
on a large pruning cut.
Inset: pruning cut protected with paint.
Handle fruit carefully to avoid damaging the skin.
•
