WA CITRUS
Is Colletotrichum affecting your citrus trees? BY DR ANDREW TAYLOR RESEARCH OFFICER PLANT PATHOLOGY, DPIRD
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n the spring and early summer period of 2020, some twig and shoot death were observed in citrus orchards around the South West region of Western Australia (WA). Although this is not uncommon, the level of damage in some orchards was higher than that seen in previous years. In some orchards, significant twig death and leaf drop were observed. These symptoms can be caused by several factors such as poor nutrition, incorrect irrigation and poor canopy management. However, disease can also be the cause. 3 TREE showing dead twigs at the extremity of the tree.
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WA Grower AUTUMN 2021
The fungus Colletotrichum, which is common throughout Australia, was isolated from samples collected from a limited number of these sites. Colletotrichum species have a broad host range and are known to cause diseases among a range of horticultural crops including stone fruit, avocado and apples. Most commonly, they are associated with the disease anthracnose.
Colletotrichum species can be found in most orchards but may not be causing economic damage. The Department of Primary Industries and Regional Development (DPIRD) is interested in hearing from commercial citrus growers who have experienced any symptoms (outlined below) in their orchards. Your reports will be a starting point to help us determine whether Colletotrichum is causing an economic impact within WA orchards.
If you see symptoms in your orchard, please take a photo and send a report via the MyPestGuide Reporter app, which can be downloaded from agric.wa.gov. au/apps/mypestguide-reporter. Make sure location settings are enabled when you create your report and send it to ‘Colletotrichum survey’. Multiple reports can be made per orchard if symptoms are seen in different cultivars or citrus species. Please add the following details to your report in the ‘I found’ section: 1 Variety 2 Severity of damage (e.g. 10 per cent of trees with symptoms) 3 Do you think these symptoms have caused economic loss (e.g. 5 per cent economic loss)?
If you see symptoms in your orchard, report via the MyPestGuide Reporter app.
