Olive oil output falls for first time in West Australia
A grower picks fifty kilos a tree one season and struggles to find a handful the next. Nothing has gone wrong. The olive is one of the most strongly alternate-bearing trees in agriculture, and understanding why explains most of what looks like crisis in harvest reports.
Every few years a headline announces that olive oil production in some region has fallen sharply for the first time, and the tone is of a young industry stumbling. Western Australia has had several such years. Growers around Gingin and Margaret River have watched a tree that yielded forty or fifty kilos of fruit deliver almost nothing the following season, with neighbouring groves reporting the opposite.
Almost none of this is a failure of skill. It is the olive behaving exactly as the olive behaves — a habit that shapes the entire world oil market, and that anyone buying, planting or reporting on olives should understand.
Alternate bearing, plainly explained
An olive tree that carries a heavy crop spends most of its stored energy on ripening fruit. Developing olives also suppress the formation of the flower buds that would produce next season’s crop. The result is a two-year rhythm: a heavy on year followed by a light off year, and the heavier the on year, the emptier the off year that follows.
Many fruit trees do this; the olive does it more severely than almost any of them. In a mature grove the swing between years can be enormous, and because whole regions tend to fall into the same rhythm — they share a climate and were often planted at the same time — national production figures swing with them. That is why world olive oil output is genuinely biennial, and why a single bad year is rarely the story it appears to be.
The winter that was too warm
The second factor is less known and increasingly important. Olives need a period of cool winter temperatures to induce flowering. Without enough of that chilling, the tree produces fewer flower buds, and a poor flowering means a poor fruit set no matter how kindly the spring behaves. A mild winter can therefore turn a scheduled off year into something considerably worse.
Then there is what happens at flowering itself. Olives are wind-pollinated and the window is short. Heat, drying winds or rain during that fortnight can strip a good flowering of its potential, and a tree can go from promising to disappointing in a matter of days. Growers have almost no control over any of it.
| Factor | What it does | How much a grower can control |
|---|---|---|
| Alternate bearing | Heavy crop suppresses next season’s flower buds | Partly — early harvest and crop thinning soften the swing |
| Winter chill | Insufficient cool weather means poor flower induction | None |
| Weather at flowering | Heat, wind or rain during the short window cuts fruit set | None |
| Pruning | Heavy pruning removes fruiting wood and cuts the coming crop | Complete — but it is a deliberate trade |
| Irrigation and nutrition | Steady water and nutrients reduce stress and stabilise yield | High, where water is available |
| Grove age | Young trees ramp up; very old trees swing harder | Only through planting decisions |
Pruning: the fall nobody should panic about
One line in harvest reports is routinely misread. When a large grove prunes heavily, its output drops the following season — sometimes dramatically. That is not damage; it is the point. Pruning removes wood, opens the canopy to light, restores the tree’s shape for mechanical harvesting and sets up better crops for years afterwards. A grower who never prunes gets a few good years and then a tangled, shaded, unpickable tree.
So a regional production figure can fall for entirely healthy reasons: an off year in the cycle, plus a mild winter, plus several major groves choosing the same season to prune. Three ordinary events, one alarming headline.
- Judge a grove or a region on a two-year average, never on a single season.
- Expect price to move with the cycle — an off year across a producing region tightens supply and lifts bulk prices.
- A heavy prune is an investment, and the year after it is supposed to look poor.
- Warm winters are the long-term worry, not any one bad harvest — chilling requirement is where a warming climate bites olives hardest.
- Southern-hemisphere oil is harvested in autumn — around April to June — so it is at its freshest when northern oil is nearly a year old.
Olive harvest swings: common questions
Why do olive harvests vary so much year to year?
Mainly alternate bearing: a heavy crop drains the tree’s reserves and suppresses the flower buds for the next season, producing a two-year on-off rhythm. Winter chill, weather at flowering and pruning decisions add to the swing.
Can growers stop alternate bearing?
Not eliminate it, but they can soften it — harvesting earlier, thinning a heavy crop, pruning strategically, and keeping water and nutrition steady. Well-managed groves still swing, just less violently.
Why does a warm winter reduce the crop?
Olives need a spell of cool winter temperatures to induce flowering. Too little chilling means fewer flower buds, and fewer flowers means less fruit regardless of how good the spring is.
Does a poor harvest mean poor-quality oil?
No — quantity and quality are separate. A small crop can produce excellent oil. What a poor regional harvest reliably affects is price, not necessarily what is in the bottle.
When is the Australian olive harvest?
Autumn in the southern hemisphere, broadly April to June, which puts Australian oil at its freshest during the northern hemisphere’s summer.
The Australian industry did something the older producing countries never quite dared: it wrote itself a tougher standard than the international one, with stricter chemistry and mandatory harvest dating, because a young industry selling against cheap imports had nothing to gain from lax rules. That is the real story behind the Australian bottle on your shelf, not any single year’s tonnage. And it points at the buying tip: a southern-hemisphere oil bought in the northern summer is typically months from the mill, while the European bottle beside it may be closing on a year. Freshness is a calendar question before it is a quality one.
Drawn from published horticultural research on olive alternate bearing and chilling requirements, and on the Australian olive industry’s own production and standards material.