Olive trees are alternative fruit bearers by nature. This means that one year the tree will bear a heavy load and the next year a lighter crop – sometimes none.
Alternative bearing is due to
- Plant Hormones
- Exhaustion of carbohydrates
Alternative bearing can be managed by manipulating certain practices such as pruning and nutrition.
NO BEARING AT ALL
It happens that olive trees don’t bear fruit at all – even for 2 to 3 consecutive years – but WHY?
Olive fruit develop from the flowers on the olive tree. Weather and / Climate conditions is the KEY reason:
- Olive trees are SELF-POLLINATORS and can also cross pollinate with certain cultivars. This happens by means of wind. When heavy rains occur during the flowering period, drenched flowers struggle to pollinate. This affects FRUIT SET.
- Flowering occurs during season change (spring) while the rains still fall occasionally and when warmer weather sets in
- The combination of wet- and warmer weather can cause humid conditions. Humid weather is excellent breeding conditions for fungal diseases that in turn affect the flowers and fruit set.
In short – untimely rain can result in poor pollination and fungal diseases and therefore problems with fruit set.
- In South Africa most olive trees are grown in the Mediterranean climate of the Western Cape.
- Olive trees thrive in Mediterranean conditions – HOWEVER – the Western Cape also have strong South Eastern winds that start blowing in Spring.
- The strong winds can literally blow off your entire crop from your tree during the flowering season!
NO FLOWERS = NO OLIVE FRUIT
- The Chill- or cold factor plays a crucial role in the olive fruit development.
- A certain degree of cold is necessary for dormancy, that in turn allows the flowers to bud.
- If the required chill factor does NOT appear, buds don’t turn into flowers and only turn into leaves and branches (Vegetative growth)
- Both DURATION and INTENSITY of the cold factor are important! The cold must be long enough and temperatures must drop sufficiently.
- On the other side of the coin, FROST also result in damaged growth and flowers DYING off.
- When olive trees undergo drought conditions, olives can appear smaller in size and also decrease in quantities.
- Continuous drought for more than one season, can lead to NO olive fruit at all.
- The trees will push all its nutrition and water into the vegetative growth in order to survive.
- When trees are not irrigated at times of extreme drought – especially during the flowering period, it can result in weaning of flowers due to the moisture stress.