Download Olive diseases in Australia

diagnostic and research work presented at national and international conferences
Olive diseases and disorders in Australia
4th European Meeting, of the IOBC/WPRS working Group Integrated Protection of Olive Crops Cordoba, Spain 2009
Important diseases and their control measures
National Olive Industry Conference & Trade Expo, Exhibition Park, Canberra, Australia, 2008
Diagnosis and detection of fungi occurring on olives in Australia
9th International Congress of Plant Pathology, Turin, Italy, 2008
Dr Vera Sergeeva
OliVera www.olivediseases.com
Objectives & outcomes: The main aim of our research is to
contribute to the knowledge on fungal diseases and disorders
of olives in Australia.
Our study has resulted in several new records of fruit rot and
root diseases and of fungi on leaves.
Based on our diagnostic and field research work we conclude
that anthracnose, cercosporiose and peacock spot are three
most important fungal diseases of olives.
This research has also resulted in new evidence of flower
infection by anthracnose pathogen leading to fruit rot.
Anthracnose on olive flowers
Flower infection
Colletotrichum gloeosporioides
cv. Manzanillo
Asymptomatic infection
of olive flowers from the early
stage of flowering to fruit set
Infected petal
infected stamens
Immature fruit infection
Colletotorichum acutatum
cv. Barnea
Fungus can be present, but dormant, in plant
tissue and will become active when fruit
begin to ripen
Fruit infected at these stages can drop; and those that remain
on the trees can exhibit sporulating colonies of fungus.
Flower infection is likely to result in
symptomatic disease expression
in mature fruits
Anthracnose on olive leaves
spore mass magnified
spore mass
spores
Brown spots carrying heavily sporulating colonies of anthracnose fungus on surface
of leaves. Spores from these leaf fungal colonies could be important sources for
secondary infection of flowers or fruits.
Different types of symptoms caused by anthracnose
Fruits caused by C.acutatum soft and leaky with orange or cream masses of fungal spores
Fruits caused by C.gloeosporioides soft or slightly sunken light brown spots
with orange or cream fungal spores
Both Colletotrichum acutatum and C.gloeosporioides species can occur in one olive grove
and fungal isolates appear to be quite diverse
Colletotrichum isolates from different states of Australia
Mummified fruits caused by anthracnose on olive tree before harvest
C.gloeosporioides cv.Manzanillo
C.acutatum cv.Barnea
Cercosporiose (Pseudocercospora cladosporioides)
P.cladosporioides has been considered as a leaf pathogen
Fruit damage may be as important as leaf infection
Cercosporiose on olive immature fruits
Green fruits develop irregular slightly sunken dark brown spots
Cercosporiose on olive fruits
Manzanillo
FS-17
On ripening olives, epidermis of infected tissues has an ash-gray
appearance, slightly sunken light brown spots
Cercosporiose
on olive fruits at harvest
cvs.Correggiola, Frantoio
Different symptoms of Cerospora leaf spot
Chlorotic spots which later develop into brown spots
These spots may be surrounded by yellow halo
Leaves showing high level of inoculum
P.Cladosporioides underside of the leaves
covered with black dust -spore mass on
green leaves without any lesions
Pseudocercospora cladosporioides on olive leaf
spore mass
Pseudocercospora cladosporioides
spores
In susceptible varieties yellowing infected leaves may fall
leaf drop and partial
defoliation of branches
Peacock spot and Cercosporiose are foliar diseases on olives.
These diseases are particularly important since it causes leaf drop and
partial defoliation of branches, which weakens the trees and reduces crop
set. Olive trees store most of their energy in their leaves.
Defoliation will result in less shoot growth, decreased fruit set, and poor
flower bud formation for the following year.
Outbreaks are sporadic, and the disease may take several years before it
becomes serious.
Not all infected leaves fall from the tree, and the fungus survives in those
that remain on the tree.
Peacock spot (Fusicladium oleagineum)
Peacock spot
After high temperatures, sometimes fungus is dead
Symptoms of peacock spot fungus detected on olive leaves
Infection on veins of leaf
Infection on leaf petiols
Inflorescence can lead to flower drop
Defoliation
Usually leaves on lower branches
of trees are first affected
Defoliation leads to loss of tree vigour
and consequently lower yield
Peacock spot (Fusicladium oleagineum) on olive fruit and stem
Stem infection
Scab
Peacock spot
Fusicladium oleagineum
spores
New records of fungal infection of olive fruits
Neofusicocum luteum
immature fruits
Neofusicocum luteum
Coleophoma oleae
Root rot diseases
Charcoal rot
Macrophomina phaseolina
Phytophthora
Phytophthora cinnamomi
Soil borne fungi
Root diseases caused by soil-inhabiting fungi can cause serious problems:
reduced growth,wilting, root necrosis and death of plant ( in severe cases)
• Phytophthora (Phytophthora cinnamomi, P.cryptogea, P.nicotianae)
• Charcoal rot (Macrophomina phaseolina)
• Rhizoctonia (Rhizoctonia spp.)
• Verticillium (Verticillium dahliae)
Rhizoctonia spp.
Verticillium dahliae
Macrophomina phaseolina
Sooty mould
Sooty mould is widespread
in olive groves, where black
scale is a problem
Olives in Australia are also subject to non-pathogenic disorders, such as
damage by heat and sun and other weather conditions, water-logging
and irregular watering or nutrient imbalances, all of, which affect the
normal physiological processes in trees.
Olive disorders caused by Frost and Chilling injuries
Frost damage
Frost is one of the most important weather
related hazards and it has caused significant
economic losses
Frost damage
Alternaria sp. secondary rots commonly infect frost/
chilling damaged fruits
Hail damage
Fruits and twigs may exhibit
open, ragged-edge to wounds
in the skin or bark
Olive disorders caused by heat and sun
Russet
Fruits continually getting wet with large
variations in temperature day time
high and night low
Sunburn
High temperatures above 40 C and
clear skies increase the incidence.
It only affects the skin does not
extend deep into the flesh
The hot Australian sun can cause sunburn in young olive trees. Since they are not
adapted to very high temperatures, they are easily injured or killed
Olive disorder - Pit burn
Softening and brown discoloration of the flesh adjacent to the stone
appeared during periods of exceptionally hot weather (few days over 40C) between
early fruit ripening and harvesting.High temperatures coinciding with excess soil
moisture may predispose the fruit to this disorders.
Leaf scorch
Hot, dry, windy weather, nutrient deficiency, poor soil and
combination of too much light and heat and insufficient moisture
Apical end rot – Soft nose
Anthracnose
Nutrition deficiency
Alternaria sp. secondary rots commonly
infect frost/chilling damaged fruit
Frost damage
Thank you