Focus Grove Project continues to bear (increased) fruit

This report outlines the status and practices of the groves taking part in the continuing Olives New Zealand Focus Grove Project. It includes observations by project consultant Dr Stuart Tustin, information from grove owners and discussions with attendees, during the fifth round of Focus Grove Visits and Field Days held in October 2021.

At Aquiferra vigorous regrowth is being left for now to ascertain stronger branches. The trees at Kakariki Olive Grove are being successful pruned for regrowth and increased production.

Hawke’s Bay: Aquiferra - Tim Groves and Jess Arthur (new owners from April 2021)

Aquiferra is one of the original Focus Groves but was also an early adopter of the grove management principles. It is regarded as an exemplary grove, with an average production in 2021 of 19.14kg/tree and 16.33% oil yield compared with regional averages of 16.65kg and 16.93% respectively.

Aquiferra had to harvest earlier than desired in 2021 due to contractor availability. The fruit was not as ripe and was difficult to shake off, with quite a lot left on the trees. Oil yield was subsequently also down and the 1700L produced was unlikely to meet forecast sales.

Tim and Jess are following previous owner Bob Marshall's 20-day spray schedule and the trees were looking clean and healthy. With flowering starting, Protek applications were being commenced as per recommendations.

Nitrogen had been added to the Manzate spray and Stuart recommended a second application. He noted that leaf tests should be done in January and July to determine initially what needs to be applied and then to gauge effectiveness, while soil tests should be done annually.

Soil testing is an indication of the ‘reservoir’ available for the tree to absorb, whereas a leaf test is what the tree can access from this reservoir. Foliar feeding then gives trees instant access to the nutrients, whereas ground application fills the reservoir and you lose control of the timing of absorption.

Stuart noted that Olives NZ recommends that once an established herbicide regime is in place, spring and autumn applications are adequate for control, the latter only if needed.

He also noted some scale has returned and recommended seeking advice from Horticentre on the spray regime required.

Pruning had been completed and regrowth was looking good on all varieties across the grove. Flowering was at different stages across the grove - in order Frantoio, Kalamata and Picual, with a two-week spread. A mild winter and lower “chilling hours” in Hawke’s Bay was most likely the cause of later and more widespread flowering times across the region.

With Hawke’s Bay in the third year of drought conditions, Stuart reminded that irrigation was needed or fruit will shrivel and impact oil yield. He recommended separating the irrigation lines to one either side of the trees to improve effectiveness.

Nelson

Note: previously Neudorf Olives has been part of the Project, following a reduced Manzate spray program. The grove has been sold and the new owners are not continuing the spray program so no field visit was conducted.

Redwood Valley: Kakariki Olives - Ray and Brenda Gregory

Another of the original Focus Groves, Kakariki has shown outstanding improvement in grove health and increased production. In 2021 the grove produced on average 14.36kg/tree and 12.98% yield, compared with the regional averages of 12.48kg and 11.62% respectively.

This result was despite major harvester issues and that around 25% of the crop was inaccessible for harvest due to overly wet ground. Picual was the highest cropping varietal at 35+kg/tree, Picholene yielded 20+kg/tree and oil yield ranged widely across varieties, with the best being 17% for Minerva.

Ray said that they had spilt their fertiliser application in two over the year, and noted that magnesium and potassium were needed.

Pruning was halfway through and it was quite evident which branch to remove on a tree - the tall ones initially left for production. There was very good leaf coverage throughout the trees, including the tall branches.

Disease control

For disease management Kakariki uses a general fertiliser, Wuxal/ NPK, added to Manzate sprays @ $30/ha. No Manzate had been applied for four months due to harvest, however, so some disease was evident. A product called Surewet has been recommended to improve spray wetting, spreading and sticking in wet conditions.

Discussion was had about licensing of products for use on olives In New Zealand, also skin sensitivity to Manzate. It was reiterated that those spraying any products, including organic, need to have done the Growsafe program to understand safe usage – e.g. the need to wash gear, including tractor and clothes, after application.

Stuart noted that Leafyridge in the Wairarapa is trialling the recommended organic approach in a separate section of their grove, aiming to reduce the use of Manzate. This is in a grove where disease is already under control, however, and the aim is rather to suppress disease not address disease problems. Monitoring will see if the organic approach is sufficient to keep disease suppressed.

An alternative to the Olives NZ organic approach, Biosea products, is also being used by an organic grove in Wairarapa, alongside a major grove renovation. *See full report online for further detail on spray options.

Flowering was just coming on through the grove and was looking very good but Stuart suggested that application now of an eradicant spray would help address current disease. An additional fungicide (Score) is added to the Manzate for two applications – now and then again after two subsequent sprays – enabling future control by the Manzate sprays. This added investment is worthwhile in a commercial grove to get on top of underlying disease and minimise impact on crop.

Canterbury: Terrace Edge, Waipara Valley - Bruce and Jill Chapman

Also one of the original Focus Groves, in 2021 Terrace Edge harvested

The trees at Terrace Edge are still undergoing renovation, with only a couple of large limbs to go.

on average 11kg/tree with a 9.53% yield, compared with the Canterbury average harvest of 10kg and 13.2% respectively. Harvest potential was probably 15kg/tree but not all trees were harvested.

The trees at Terrace Edge are now probably half the size they were when the project started and regeneration has been very effective. Trees are open with light penetration throughout and are looking really healthy, however Stuart cautioned the need to do Protek sprays to suppress Anthracnose. The trees are full of flowers, right through the canopy.

Stuart noted that tree width should be kept within the machine harvest umbrella and that where disease is already under control, the

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The unharvested trees at Two Old Soldiers enabled a demonstration of machine shaker harvesting (above and below).

aim is rather to suppress disease not address disease problems.

Also that branches with no leaves for several metres are part of the legacy of the trees but the aim to bring the canopy down will see these removed in due course.

Foliar leaf tests are looking good. With calcium and magnesium a little light, a boron, iron and magnesium foliar spray was planned. A soil test each spring was also recommended to address any issues before fruit set.

Clover was noted as good ground cover, contributing nitrogen, and an alternative to using herbicide. Olives NZ now promotes only doing one, maximum two, herbicide sprays per year. Also leaving mowing a bit longer, creating a sward which when cut becomes a mulch. Mowing should be short prior to hand harvesting, however.

Disease Management

With the first application of Protek due, Terrace Edge was looking at introducing a more organic approach, especially as disease was much more under control.

Serenade and copper products were discussed by attendees as organic alternatives to Protek and Manzate. The copper program is four sprays per year and boron is also applied.

Stuart noted that this program is not sustainable, as the grove in question was previously sprayed monthly and is carrying the benefits of that regime but undoubtedly disease will become a problem again. The Olives NZ organic option has been based on success in other crops and frequency of spraying is integral, as with Manzate, in suppressing disease.

A heavy fertilizer program can also mask disease through vigorous external growth, which leads to poor productivity.

It was noted also that New Zealand does not have the olive pests that cause major problems in Europe and Australia, therefore the antifungal program is the only regime needed.

Two Old Soldiers, Waipara Valley - Gordon Legge and Louise Webb

A visit to neighbouring property Two Old Soldiers Grove enabled demonstrations of machine shaker harvesting and how to rejuvenate neglected trees, as the grove had not been harvested or pruned.

The trees were still laden with black fruit, some estimated at 25kg. The density of the unpruned trees impacted the fruit removal, however around 15kg per tree was harvested. The trees were starting to grow the next ring of trunk growth and quite soft, so there was a bit of trunk damage from the clamp.

Overall the trees were in poor shape, with dead wood in the canopy and a lot of disease. There was little new growth for subsequent fruiting and no budding, while other groves in the area were already in bud, so there would not be much to harvest in 2022. It was noted that there had been no crop for the previous two years and if left, this pattern will continue or worsen.

Stuart pointed out there was no regenerative growth on old pruning cuts because the canopy is full of dead wood and blocking light penetration. The trees need transformation to stimulate regrowth and the tree height needs to be controlled with big low branch

At Leafyridge Stuart used a pole saw to remove old dead branches, to open up for light and remove dead wood that encourages Anthracnose.

Tip scorch at Leafyridge was minimal among otherwise healthy, green leaves, therefore would be monitored but was of no great concern. With several years of remediation work still needed at Bella Olea, many of the trees have substantial amounts of dead wood and lichen in the canopy.

cuts. While pruning after harvest is ideal, this can be done through flowering if needed. Use Barkseal or similar on major cuts.

It was noted that Leccino needs a longer stump to enable regrowth, different from other varieties. A very tall tree can have 1-2 branches removed each year over a period or be coppiced. Large branches are good for firewood and everything else can be mulched back into grove.

Also that pruning is different for hand held branch shakers, where you want a shorter and more spread tree.

Wairarapa: Leafyridge Olive Grove, Masterton - Craig and Ruth Leaf-Wright

Leafyridge is an original Focus Grove, where aggressive pruning has restored good tree shape and size, and seen a dramatic increase in productivity. The average harvest for 2021 was 18kg/tree and oil yield 16%, while the regional average was 12.13kg and 13.75%.

Craig noted that the Focus Grove Project has seemingly addressed biennial fruiting for those following the program. Pruning was due to start shortly and the Leafyridge trees were looking very healthy, full of green, healthy leaves and with new buds right through the canopy. With luck and good management there will be another good crop in 2022.

Stuart said from fruit set onwards to watch that shoots are growing 20cm from new olives, as short shoots support minimal fruit the following year. If new growth is not apparent and the crop is looking good, cut out some branches, especially those blocking spray penetration or outside the harvest umbrella. This will allow the tree to put more effort into extension growth.

Nutrition

Copper oxide had been applied in late July and also Seaweed Pronto. Leaf tip scorch in one block was thought to be potassium or magnesium deficiency, however recent leaf test results showed potassium at medium to high levels. Magnesium was on the low side, as was nitrogen, and urea had been applied. As the tip scorch was minimal among healthy, green leaves, the issue would be monitored but was of no great concern.

Disease management

The last Manzate application prior to harvest had been mid-April and the next in late July, with signs of Peacock Spot emerging from the intervening period. Craig may look at splitting the harvest to minimise the break in the spray regime. While a good approach to managing disease, Stuart pointed out the reality that there would always be some disease present.

He suggested the eradicant regime post-harvest to kill the fungus rather than suppressing it.

There is also now an organic trial block at Leafyridge, well separated from the rest of the grove, using sulphur and copper rather than Manzate as per the ONZ Organic Fact Sheet program. This trial was driven by some negative feedback from consumers about the use of Manzate and provides an observation project comparing the traditional method vs the organic method. Stuart noted that Leafyridge was ideal to carry out this trial as the grove was in an excellent condition to start with.

The organic sprays and Manzate have both been applied approximately three weeks apart since the end of harvest.

With flowering starting, three Protek sprays will be applied as per recommendations, and Serenade will be used on the organic trial block. This is very expensive compared to Protek (approx. four times the cost), however Stuart said two applications should be sufficient and help reduce cost.

Bella Olea, Greytown - Chris and Hilary Penman

The Penmans are following an organic approach and should achieve full certification shortly. In 2021 Bella Olea harvested on average 10.77kg/tree, similar to the national average, with the Leccino cropping at almost 20kg/tree.

Insufficient spray application has seen disease return to the Bella Olea grove.

Substantial pruning has already been carried out but there is another two to three years’ work required to remediate the grove, as the trees are still very tall. Quite a lot of new buds have been eaten by the sheep that graze the grove, which could be addressed by increasing branch height. Chris said he intends to continue to use sheep for weed control and their wool for mulch.

Unfortunately the majority of trees were not looking good, with little new growth and lots of dead wood and lichen. Previous cuts have few shoots and many lack leaves. It was encouraging to see the amount of flowers on some trees/varieties, however there was nothing on the Frantoio. This grove is still in biennial production mode, as there was a huge flowering last year.

Nutrition

Chris wanted to know how much Nitrogen he removes with the olive crop so he can replace this with his fertiliser program to improve grove nutrition. Stuart agreed that all growers should use this information to inform nutrition/fertiliser program specific to their groves and varieties. He undertook to track down this information for Olives NZ to circulate.

Disease management

Biogro certified products are used exclusively at Bella Olea, including Biosea for both disease management and nutrition, at an application rate of 500L/ha. Spraying was not being done monthly as recommended, however, and it was disappointing to see the level of disease across the grove. It had gone backwards from April, when it had been looking really good, and it was apparent that insufficient spray application has seen disease return.

A sulphur spray is being looked into to address the amount of lichen in the trees, which shakes off with olives going to the press (fortunately removed by a good leaf removal system). Stuart recommended Kumulus to address the lichen issue, alternated with Biosea, which should also help reduce Peacock Spot.

Comment was made that the trees were too big for the application rate, which should be doubled to 1000L/ha.

With renovation now complete, flowering on the healthy Olives on The Hill trees was looking very promising.

Average crop harvested doubled

When the initial Focus Grove Project started the national average of crop harvested in New Zealand groves was less than 5kg/tree. This has been lifted to 10kg for the first time this year thanks to the increased productivity and efficiencies produced by the FGP’s recommended management practices. The initial project target for Focus Groves was an increase to 15kg/tree average crop, however the substantially higher average harvest of 25kg/tree was achieved. The current project aims to lift the average by another 5kg to 30kg/tree. Typically the Focus Groves significantly out-perform their regional average and in 2020, a second run at Leafyridge with branch shakers following the machine harvesting achieved an additional 5-10kg/tree - more than many groves’ total harvest.

Northland: Olives on The Hill - Chris and Linda Smith

Like many of the other original Focus Groves, Olives on The Hill has seen continuous improvement to overall grove health and increased grove production. Production in 2021 was an average of 6.09kg/tree and 15% yield, compared to Northland regional averages of 3.87kg and 16.3% respectively.

Note: COVID travel restrictions meant a Northland field visit had to be postponed until the March 22 round, so an update was provided by Linda.

“The grove was subdivided in March/April, reducing trees from 1300 to 785. The main varieties are Frantoio and Leccino, with a few Ascolano, Barnea and Manzanillo.

The renovation process is pretty much completed and the size of the trees is quite different from the huge ones we started with.

Chris has applied Protec, along with the Manzate, since the flowers first appeared (three times). We have also applied a fertilizer mix containing lime, potash, phosphate, kieserite, sulphur and boron.

The trees are loaded with flower at the moment, so we are hopeful for a good harvest next year.”

This is an edited version of the Milestone MS05 report of the Sustainable Farming Fund Project 19025 - Meeting the increasing demand for New Zealand Extra Virgin Olive Oil.

The full report, and further detail about the project, can be found on the Olives New Zealand website: www.olivesnz.org.nz.