Olive leaf, flower and fruit samples are wanted for a three-year research project into pest and disease management being conducted by the University of Western Sydney.
The project, which began during the flowering period in the 2006-07 season, is investigating olive fruit diseases and disorders, and the safe use of fungicides to manage berry rot diseases for sustainable olive culture.
The research team consists of Associate Professor Robert Spooner-Hart, Dr. Vera Sergeeva, Oleg Nicetic, and Associate Professor Tan Nair and the project is supported with financial grants from Horticulture Australia Ltd, NuFarm Australia and Boundary Bend Management.
The olive industry does not at present have any registered fungicides except copper for use in disease management, yet it is often not realised that fungal pathogens can taint olive oil. For instance, more than 30% infection of olive berries by anthracnose (Colletotrichum spp.) has been shown to result in increased free acidity and peroxide numbers in the oil. Such oil could not be considered extra virgin.
Anthracnose, caused by the fungi Colletotrichum gloeosporiodes and C. accutatum, is a widespread olive disease occurring in most of the major olivegrowing countries of the world. It causes a soft rot on olive fruits. Under favourable conditions it produces orange slimy masses of spores on the fruit.
Berry rots
Symptoms of Colletotrichum infection appear on fruit, normally during ripening. Infected fruit show soft, brown tissues on the shoulder part and are covered with concentric rings of massive amounts of orange spores. Some fruit are completely covered with the sporulating (reproducing spores) or sunken spots. Apart from anthracnose, we have also identified Cercosporiose caused by the fungus Pseudocercospora cladosporioides on fruit as well as leaves. Both are important diseases in a number of olive-growing districts in Australia. However, growers can find it difficult to correctly identify these diseases, as symptoms can look similar. While most growers have heard of anthracnose, fewer have heard of cercosporiose disease.
The work the research team believes needs to be undertaken on Anthracnose and Cercosporiose of olives includes:
• the biology of these species in Australia
• the source of inocula
• pathogenicity on different olive varieties
• the timing of disease infection
• assessing the efficacy of fungicides
• optimizing timing and application of fungicides in the field
Field monitoring
We are interested in receiving olive fruit with any symptoms of rot or similar damage, to better understand the extent and distribution of the fruit diseases and disorders present in Australia.
How and where to send your samples
The success of this project will be greatly enhanced through the participation of olivegrowers. Growers can assist by sending samples of fruit and leaves between now and harvest. Samples showing any type of symptoms can be sent, and this is particularly important if there has been a history of fruit rots in the grove. Samples should be packed in paper bags after wrapping fruit and leaves separately. They can be posted during the early part of the week to avoid weekend storage in transit. The samples heed to be labelled including the name of olive variety, stage of olive growth, date of collection and locality, including grower contact details.
The mailing address is Dr Vera Sergeeva, Centre for Food and Plant Science, University of Western Sydney, Locked Bag 1797, South Penrith DC, NSW 1797. The contact details for Dr Sergeeva are: Mobile: 0425 377 384, Fax: (02) 4570 1314, and email: v.sergeeva@uws.edu.au.
