Pests & Diseases » Peacock Spot
Peacock spot (Spilocaea oleaginea) is a widespread fungal disease of olive trees
The disease requires moist warm conditions to develop and usually becomes prevalent in autumn and spring. Small sooty blotches develop on the leaves, which in time grow into greenish-black circular spots that measure 2 to 10mm in diameter.
A faint yellow halo is often evident in the tissue around the spots. As the disease develops the leaves become yellow and fall. Most of the infected leaves will fall prematurely by the start of summer. In severely infected trees complete defoliation can occur.
Peacock spot is best managed by applying a preventive copper spray in late autumn. A second application in late winter is also recommended in areas subject to warm winters and spring rainfall. If you missed these sprays an application in spring is recommended to prevent inoculum slowly building up and causing a major disease problem down the track. Two fungicides are currently registered for the control of Peacock spot in olives: copper oxychloride (rate-4g/L) and copper hydroxide (Kocide, rate-2g/L)).
When both a fungicide and insecticide need to be applied at the same time, mixing the two together in the same spray tank can reduce spray operations. The compatibility of various chemicals can be checked on the product label or by contacting the manufacturer.
It is not recommend that chemical treatments are applied to the trees during flowering as some chemicals cause flower abscission and disrupt fertilisation and subsequent fruit set.
Please note it is a legal requirement that label instructions are followed, if olives are not listed on the label of the pesticide, it is either not registered for use on olives or an off label permit is required.
Pesticide registrations and off-label permits for olives can be viewed and downloaded from the Australian Pesticides & Veterinary Medicines Authority website: http://www.apvma.gov.au (click on search for a permit tab then enter olive under the crop section).