Olive growers delighted that technique used for fruit trees doubles their harvest

The Smith family of Olives on the Hill at Mangawhai. From left, Chris, Linda, Emma and Neil. Photo / supplied

Startling results from a research project have at least doubled olive yields to the delight of growers at trial sites across New Zealand.

The three-year research project was conducted by Olives New Zealand and funded by Ministry for Primary Industries' Sustainable Farming Fund.

One of the trial sites was at Olives on the Hill in Mangawhai, Northland, which is owned by Linda and Chris Smith.

Linda says olives "grow like weeds" in Northland's warm and wet climate, with the challenge to keep trees under control and ensure harvests are completed before fungal diseases can affect the crop.

Using New Zealand fruit tree management techniques instead of olive grove management methods of arid climates in the Northern Hemisphere and Australia has made a huge difference.

The Smith's harvest has grown from 10kg per tree to between 25kg and 35kg.
This year is looking like also being a heavy crop and will be harvested in April and May.

Linda says previously the grove was almost biannual, with a light crop every second year.
"With these new management techniques, it looks like we have managed to knock that out, which is what we've been aiming for," she says.

"We want a consistent harvest every year."

The Smiths were cycling during a holiday at Mangawhai Heads in 2012 when they saw a sign on a gate saying: "For Sale, Olive Grove".

The 10-year-old grove was very neglected with waist-high grass and a lot of dead wood on the trees so that it was impossible to walk down the rows.

Knocking it into shape included coppicing some of the varieties that were more susceptible to disease to waist height. "It looked a bit like a war zone for a bit. There was a paddock of stumps," Linda says.

"We played with it for a year and had such fun with it that we decided to build a house on the property and move up from Auckland. Our son, Neil, has gone on to do a degree in horticulture at Massey University and works in the olive industry in the Hawkes Bay so he can help us as well.

"It was a huge learning curve, but luckily we got involved with the Olives New Zealand focus grove project that was just starting.

"We've gone from knowing very little to now knowing a little more. There is still so much to learn.'' she says.

Dr Stuart Tustin from Plant and Food at a focus grove meeting. Photo / supplied

The Olives New Zealand research project involved Dr Stuart Tustin, a fruit tree physiologist from Plant and Food Research, and Andrew Taylor, an olive industry consultant. They both have extensive knowledge of stone, apple and pear culture and suggested applying methods that work for stone fruit crops to the olive trees.
These include more aggressive pruning, a proactive spraying programme every 21 days and thinning crops after the fruit has set.

New Zealand olive trees tend to have more problems with fungal diseases such as cercospora, peacock spot and anthracnose which are enhanced by Northland's wet climate.

Once these diseases are under control and the trees are pruned well, the growers have found they are able to grow large clusters of olives for the first time – like bunches of grapes.

Olives New Zealand recently received funding from MPI's Sustainable Food & Fibre Futures for an extended research programme for another three years to see if production can be improved more. This has replaced the Sustainable Farming Fund.

The new research project aims to produce another 5kg per tree and will include revising harvesting methods.

It will also trial organic methods of production, including the use of organic sprays.

Linda says while their 1300-tree grove cannot compete with volume on a global scale, they "can compete on quality".

Currently they sell their products online and at local markets and supply some select restaurants.

And like holidaymakers in Mangawhai at the moment, she is hoping for as much sun as possible over the next few months to make their extra virgin olive oil the best it can be.