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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