diagnostic and research work presented at national and international conferences

Transcription

1 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

2 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.

3 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 stamens Immature fruit infection Colletotorichum acutatum cv. Barnea Infected petal 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

4 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.

5 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

6 Colletotrichum isolates from different states of Australia

7 Mummified fruits caused by anthracnose on olive tree before harvest C.gloeosporioides cv.manzanillo C.acutatum cv.barnea

8 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

9 Cercosporiose on olive fruits Manzanillo FS-17 On ripening olives, epidermis of infected tissues has an ash-gray appearance, slightly sunken light brown spots

10 Cercosporiose on olive fruits at harvest cvs.correggiola, Frantoio

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12 Different symptoms of Cerospora leaf spot Chlorotic spots which later develop into brown spots These spots may be surrounded by yellow halo

13 Leaves showing high level of inoculum P.Cladosporioides underside of the leaves covered with black dust -spore mass on green leaves without any lesions

14 Pseudocercospora cladosporioides on olive leaf spore mass

15 Pseudocercospora cladosporioides spores

16 In susceptible varieties yellowing infected leaves may fall

17 leaf drop and partial defoliation of branches

18 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.

19 Peacock spot (Fusicladium oleagineum)

20 Peacock spot After high temperatures, sometimes fungus is dead

21 Symptoms of peacock spot fungus detected on olive leaves Infection on veins of leaf Infection on leaf petiols

22 Inflorescence can lead to flower drop

23 Usually leaves on lower branches of trees are first affected Defoliation

24 Defoliation leads to loss of tree vigour and consequently lower yield

25 Peacock spot (Fusicladium oleagineum) on olive fruit and stem Stem infection

26 Peacock spot Scab

27 Fusicladium oleagineum spores

28 New records of fungal infection of olive fruits Neofusicocum luteum immature fruits Neofusicocum luteum Coleophoma oleae

29 Root rot diseases Charcoal rot Macrophomina phaseolina Phytophthora Phytophthora cinnamomi

30 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) Macrophomina phaseolina Verticillium dahliae Rhizoctonia spp.

31 Sooty mould Sooty mould is widespread in olive groves, where black scale is a problem

32 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.

33 Olive disorders caused by Frost and Chilling injuries

34 Frost damage Frost is one of the most important weather related hazards and it has caused significant economic losses

35 Alternaria sp. secondary rots commonly infect frost/ chilling damaged fruits Frost damage

36 Hail damage Fruits and twigs may exhibit open, ragged-edge to wounds in the skin or bark

37 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

38 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

39 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.

40 Leaf scorch Hot, dry, windy weather, nutrient deficiency, poor soil and combination of too much light and heat and insufficient moisture

41 Apical end rot Soft nose Nutrition deficiency Anthracnose Alternaria sp. secondary rots commonly infect frost/chilling damaged fruit Frost damage

42 Thank you