Beyond the cost barrier: Netting delivers growthBusiness Management
As APAL campaigns for support for growers to address the high cost-barrier to netting to protect crops, those who have been able to net report benefits beyond risk management including improved yields and packouts and labour and water savings, improving long-term sustainability and decision-making.
Western Australian growers Michael and Kaye Fox and son Mat took the plunge and started netting their orchard in the state’s south west after being badly hit by hail in 2013. Like many others, motivation to net was primarily risk mitigation.
“The hail damage created a substantial financial loss and we became very nervous about the growing season after that,” Mat said.
The family started installing 16mm hexagonal net, erected with a permanent structure, in 2014.
By August this year, 15 hectares of the 17-ha high-density orchard – 75 per cent apples: 25 per cent avocados – will be under net at an outlay of around $0.75 million.
Mat said while it would take years to repay the investment in monetary terms, it had begun returning in increased production in the first season.
“Netting is still a bit new to us; once we finish netting most of the trees this year, we’ll be able to work out how much netting has improved packout across the orchard,” Mat said.
“In the summer, you don’t have to allocate a labour unit to scare birds away. And you pick the number of apples you expect to pick – outside the net, you need to leave about another 50 apples on the tree just for the birds.”
Hailstorms represent the most frequent and – on an annual aggregate basis – the highest losses for the insurance industry in Australia.
Climate change is predicted to make extreme events more frequent and more severe.
As growers across the country know to their cost, it does not take much damage to see the crop downgraded to processing. Hail can wipe out the majority of the value of the crop in a very short time. Insurance is either unobtainable or prohibitively expensive.
That leaves growers with the daunting challenge of raising the substantial $60,000+/ha required to net. Netting also creates a new microclimate and set of management challenges.
The Foxes’ experience, shared by others, is that if the cost barrier and management challenges can be overcome, netting can provide a range of benefits that, in addition to reducing risk, may make the business more profitable and more sustainable longer term.
Yield and water efficiency
A Western Australian netting trial study (2013–16) carried out by Agriculture WA on the commercial orchard at Manjimup owned by Mauri and Ann Lyster, looked at netting and non-netting scenarios for producing marketable fruit. Sunburn was twice to four times more prevalent on apples from trees without netting and the percentage of marketable fruit in the packout was higher under nets. Fruit tended to be on average 10g heavier and more prolific when grown under black net, compared to white net; but the average size of the fruit hardly varied.
One reason given was the fruit stayed longer on the tree because it took longer for the blush to rise; a secondary reason was increased leaf cover on trees under net, which also lengthened ripening time.
Irrigation use was reduced by 60 per cent, first by installing drip infrastructure across the whole site in the 2015–16 year of the trial in response to increased vigour under nets, and then reduced again to 1.7ML/ha under the nets, compared to using 2ML/ha outside.
Changing the microclimate
Permanent structures that hold the net 4.5m–5m above the ground, change the orchard management requirements, not least because they automatically impose a limitation of 4m–4.5m on the height of trees and 3m on the available width between rows for machinery to pass.
One of the issues to manage under permanent nets is the changed microclimate.
A well-understood and significant benefit of increased shade is reduced sunburn damage – sunburn typically occurs when fruit surface temperatures rise above 45°C.
However, changing the microclimate has knock-on effects on tree vigour, pollination and pest management, all of which require their
Jason Shields, orchard manager at Plunkett Orchards, Ardmona, Victoria, is confident of the return on investment from netting, but actively manages for microclimate and sunburn.
The 150ha farm, 87:13 apples and pears, has 36ha of fruit netted. The oldest netting block is 12 years old. About 50 per cent is fixed netting and 50 per cent is retractable – the retractable net remains on the superstructure but is pulled up as soon as harvest is finished. The labour cost is offset by increased production.
“Sunburn damage to the Granny Smith apples has reduced by 30–40 per cent under the nets and with an improvement of 10–20 per cent on skin marks,” Jason said. “That’s a substantial increase in production.
“Trees under the net have more vigour and grow stronger, but the bud development is poorer.”
Managing pollination in a covered or enclosed area is one of the challenges of netting and a work still in progress by researchers. New funding for further research into pollination under nets was announced by Hort Innovation mid-year. Jason encourages pollination by introducing bees in hives.
Another 25ha of trees will be under net by the end of this year, with a forecast improved packout of 25 per cent.
Jason has calculated a 12 per cent better packout on Pink Lady apples, quantified at $7000/ha return on investment (ROI) per year post-netting; and a 25 per cent better packout ($10–$11,000/ha ROI) on the Granny Smith.
“It increases production up to 75–80t across the whole orchard,” Jason said. “An increased 10t packout of the Pink Lady apples gives payback within the first year.”
Jason has seen a drop in the need to spray for mites, but an increased need to be on the lookout for powdery mildew. The orchard also uses at least 30 per cent less irrigation under net.
No free lunch for birds
Maximising packout of first and second-class apples saw South Australian grower Joe Ceravolo invest initially in drape netting 20 years ago, and more recently in permanent flat top netting, in five orchards across 150 ha in the Adelaide Hills, at a cost of $50–$60,000/ha.
Bird pressure was the biggest management issue, with sunburn secondary and moisture and heat stress tertiary concerns.
“Netting improves the quality of fruit we grow,” Joe said. “There are 40 per cent more Granny Smith apples in the first and second-class pick; sunburn is reduced from 20 per cent to three per cent under the grey net. That gives us an improvement of 18 per cent increase in production. Netting also helps to reduce our water use considerably.”
Joe said the main reason for netting had been to eliminate the food source early for birds. He anticipates flying foxes may also be in issue in the not-too-distant future.
“Once the birds come in and start eating, they keep banqueting,” he said “This year we lost 100 per cent of a patch of Gala apples, three weeks before picking was to begin. In the second patch, we lost 60 per cent of the Gala, even though we put up drape nets. Never underestimate a bird’s intelligence.
“When you lose 50 bins of apples, how can you not warrant the netting?
“For efficiency, we converted to permanent flat top fully-enclosed netting 12 years ago. Initially we used Netpro over existing plantings. It’s purely an economic decision to use different nettings.”
Increased packout a standout
While birds are also an issue for fellow South Australian grower Robert Green, hail-protection was the main driver for netting, with the promise of higher quality and packouts reinforcing the case.
“Parrots and lorikeets are becoming a pest species for the crop,” Robert said. “The big driving factor for us is the increased potential for heatwaves and hail risk. We asked ourselves, what does business look like if we get a hail event?”
The fourth generation Lenswood orchardist, with wife Nicola and father Ross, has 40,000 trees in the Adelaide Hills, planted at a density of 3000/ha. Nets were installed at 4.5m high, supported by steel structures, at a cost of $55–$65,000/ha; designed to release hail loads to deposit safely between tree rows.
When it did hail, in 2017 and 2018, 80 per cent of the orchard was covered by nets.
Research by Apple & Pear Growers Association of SA, found that in 2017, an average 19 per cent of fruit under hail nets was damaged, compared to 61 per cent in orchards without nets; in 2018 when hail was accompanied by high wind speeds, an average 30 per cent of netted fruit and trees were damaged, compared to 64 per cent of non-netted crops.
Although more expensive, the trellis-release style of netting showed lower likelihood of damaged fruit, and limited damage to trees when the end post structures were erected on a lean.
Robert sees the benefits as reduced storm-damage potential, decreased sunburn and bird damage and increased water savings under the net.
But it was the increased packout that really stood out, as well as the capacity for the workforce to work longer hours under the net, picking with increased UV protection.
“Within two years of netting, it was obvious we were getting increased first-class packout and a 20 per cent increase in productivity,” Robert said. “The recoup on expenditure is not there quickly. But I can sleep without worrying about storm damage.”
Robert sees value in a subsidy to net orchards, given the environmental benefits of such a move; but believes it should also apply to replacing worn or damaged nets to ensure protection can be maintained.
It’s a view echoed by other orchardists.
Hardings Orchard at Pakenham, Victoria, was an early adopter of netting, after losing the entire 490t crop to a hailstorm on Australia Day, 1998.
he cantilevered poles with permanent netting attached, at a cost of $18,000/acre ($45,000/ha), was recouped from the increased production of first-class apples. A subsequent hailstorm in March 2010 caused about $100,000 damage to the net and established trees in half the orchard.
“About 90 per cent of the net in that half of the orchard was damaged and needed replacing. We also lost some of the older trees,” Marie Harding said.
“The cost of insuring net and its supporting infrastructure isn’t cost effective.”
No other option
Ian Armour, of Armours Apples, Bona Vista, Victoria, has experienced hail in 10-centimetre deep drifts on the ground, but agrees insurance
is not a viable option.
“Hail insurance premiums tend to be higher than the profit you make on the apples,” Ian said.
About 85 per cent of his 40ha apple orchard is netted to 5m high on a steel superstructure from SA-based JA Grigson that integrates the trellis. This year he is adding side netting to exclude the increased predation of flying foxes and birds.
There are issues to manage– colour comes in later under net and there is increased powdery mildew and woolly aphid damage, which Ian manages by spraying.
Netting at 5m high gives some cross breeze which benefits bee movement and the health of the trees,” Ian said.
“But when you’re blocking the sides in to avoid flying fox damage, you’re reducing biodiversity because you’re excluding little birds that naturally control insects.”
Assisting wildlife and food-production to co-exist may be another argument for assisting orchards to net, he suggests.
“If the community wants an environment with flying foxes, you could subsidise installing net that excludes them from orchards.”