Olive anthracnose

What you see

Ripening olives develop sunken brown patches that soften, and in humid weather ooze a distinctive orange-pink slime of spores. Fruit shrivels to a mummy and drops. Twigs die back and leaves yellow above affected fruit.

Conditions

Warm autumn rain during ripening - the single most damaging combination for olives on this coast. Late-harvested and late-ripening fruit is most exposed.

Treatment

Harvest promptly once fruit begins to colour rather than leaving it hanging into the autumn rains. Remove mummified fruit. Copper before the autumn rains set in.

Prevention

Choose less susceptible varieties. Prune for an open, quick-drying canopy. Do not leave dropped fruit under the tree over winter.

Months: September, October, November, December

Plants

Olive

Remedies

Bordeaux mixture (copper)

The thing people get wrong

Gafa is the reason a Portuguese olive harvest is a race against the first serious autumn rains, and it wrecks oil quality long before it makes the fruit look bad - acidity climbs sharply in fruit that is infected but still looks acceptable. If rain is forecast for a week and the fruit has coloured, picking early beats picking ripe.