Anthracnose (Colletotrichum gloeosporoides) can be a problem on ripening olives, especially in moist conditions, but it can be controlled with strategically timed copper sprays. Anthracnose causes soft, circular rots on fruit close to harvest time. The spores live on in infected, mummified fruit. This is another reason why it is important to harvest the entire crop and rake up and bin any windfall.
A condition known as soft nose is sometimes mistaken for anthracnose. It causes blistering and crinkling at the bottom and side of the fruit, about a month before harvest. Soft nose is a nutritional disorder which is believed to be influenced by factors such as climatic fluctuations. A calcium spray in early summer is recommended to combat soft nose.
Also known by the common names of olive leaf spot and bird’s-eye spot, peacock spot is caused by the fungus Venturia oleaginea which is present in Australia but is not reported from Western Australia. It causes faint round lesions on olive leaves, which develop into dark spots with yellow haloes. The disease can cause leaf-drop, occasionally to the point of complete defoliation, and poor fruit-set. The fungus survives through winter on infected leaves.
The Department of Agriculture and Food, Western Australia (DAFWA) is on the lookout for animal and plant pests, diseases and weeds that could pose a threat to agriculture and the environment.
If you discover something unfamiliar, please send a photo to the Pest and Disease Information Service (PaDIS) by email: firstname.lastname@example.org or phone them on Freecall: 1800 084 881.
Please read the sending specimens for identification web article before sending, or bringing in, samples to the Pest and Disease Information Service, 3 Baron-Hay Court, South Perth, 6151, WA.