WHEN OLIVE TREES BEAR FRUIT AND WHEN NOT
Written and compiled by Alinda van Dyk
I often get this question from our customers and recently a gentleman asked me:
“Why will my olive tree bear fruit HEAVILY one year and then absolutely nothing for two consecutive years?”
I decided to focus my blog on this issue – especially as olive trees are now flowering and fruit are setting as we speak…
WHERE DO OLIVE FRUIT COME FROM?
The buds that develop into flowers, in turn become the olive fruit. Sometimes the buds don’t flower into FRUIT but only develop into VEGETATIVE GROWTH.
Here are a couple of reasons why olive trees bear little olive fruit, or on occasion even nothing at all:
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.
SOLUTIONS AND CONSIDERATIONS ON HOW TO MANAGE OLIVE FRUIT BEARING
Remember – it is easier to manage your olive tree in your garden, than it is on a large agricultural scale.
- An olive tree needs to grow in a Mediterranean climate:
- During drought conditions, be sure to water your garden olive tree during budding
- Plant your olive tree where it is protected from strong South Eastern spring winds (This of course is easier on a non-commercial scale)
- Be aware of and manage fungal diseases on the olive buds during humid weather conditions.
2. CULTIVAR CHOICE (VARIETY)
- The cultivar choice of your olive tree is a CRUCIAL KEY factor that plays a role in olive fruit set.
- As the intensity and duration of the chill factor plays an important role in olive fruit set, one has to consider how intense your winter is in the place you intend to grow your olive tree.
- It is important to know where certain cultivars were developed i.e. the ORIGIN
Spanish Cultivars are used to a 7ºC temperature for an average of 300 hours.
Italian cultivars might be the same temperature BUT require longer cold hours e.g. up to 600 hours.
If you have short winters – plant olive trees with lower chill unit requirements such as Spanish and Tunesian cultivars
Italian cultivars such as Leccino require long winters with high chill units
3. ALTERNATIVE OLIVE BEARING
- Alternative olive bearing CAN be managed!
- Correct nutritional- and pruning management of your olive tree will have a positive impact on the hormonal and carbohydrate activity.
Pruning and nutrition tips
Nitrogen is the one nutrient that olive trees can easily be deficient in. This affects the fruit set directly. Give your tree an Urea treatment during the spring growth period.
When pruning – cut out dead, dense and crossing branches. Cut shoot tips to enhance lower branch budding.
CARING = BEARING
Contrary to many misbeliefs, an olive tree is NOT a desert plant
A nurtured olive tree is a happy tree and will reward you with plenty olives to enjoy!
WILLOW CREEK HAS A LARGE OLIVE NURSERY WITH A WIDE RANGE OF OLIVE CULTIVARS.
If this blog has inspired you to start a small olive grove, or perhaps to bring some peace to your garden with a couple of olive trees – why not visit our OLIVE NURSERY on the farm in the Nuy Valley. The nursery has a wide range of cultivars and our farm manager will gladly assist in choosing the right cultivar for you needs.
Contact firstname.lastname@example.org to obtain more information about our nursery or click on this link to visit our nursery page on our website.