Olive Growing
Orchard Management - Pest and Disease Management
Olive pests are, to a large degree, kept in check by their natural enemies in the Western Cape. Olives thus lend themselves here to be grown and marketed as organic products. Growers should be careful not to disturb this balance by injudicious pesticide use, and should in addition use other practices which can reduce pest infestation, such as correct pruning and minimising traffic dust.
The main pests which occur on olives in South Africa are:
- the yellow and black striped olive beetle, with its bright yellow larvae which eats and tunnels into leaves especially on young trees, destroying new growth.
- the olive lace bug or “tingid” which sucks out the sap of leaves, especially where growth is dense, and so causes tiny yellow dots on the leaves which later become completely chlorotic and die.
- the olive fly, which stings the fruit and lays its eggs which then hatch and destroy the fruit as the larvae burrow through the flesh.
Under dusty conditions, infestation by various scale insects can be damaging. Insects such as psylla only become serious pests when the ecological balance is disturbed through injudicious pesticide use. Effective control of most of these pests is available, but one should always strive to allow biological control to take place.
The main fungal diseases include:
- anthracnose (“Gloeosporium”), which causes rapid fruit spoilage and cankers on shoots;
- olive leaf spot (“peacock spot”) which causes sooty spots and yellowing of leaves, later resulting in leaf drop and death of shoots;
- various soil-borne root diseases (Phytophthora, Verticillium, Phoma, etc.) which occur as a result of poor irrigation scheduling (localised over-irrigation and excess free water at the tree stem).
These diseases are controlled by chemical agents and correct orchard management practices.