Oakmoor Orchard is around 250 ha of modern orchard at Ardmona near Shepparton in Victoria. The orchards are spread over five sites. Oakmoor produces apples, pears, peaches, nectarines, apricots and plums with a total production of approximately 8,000 tonnes of fresh, packed fruit per year. It produces around 2,000 tonnes of Granny Smith and Pinklady apples per year.
All apples, especially Granny Smith apples, are susceptible to sun burn or heat stress. This occurs during heatwaves, such as those experienced in February 2013 and February 2014, as the fruit is maturing. A 2009 report by The Department of Environment and Primary Industries, Victoria (DEPI) estimate that 6% to 30% of overall apple and pear losses and 40% of Granny Smith apples, are due to heat stress. In 2013, Oakmoor's Granny Smiths suffered losses of up to 30% from sunburn.
'Supermarkets and export customers require that only cosmetically perfect fruit be delivered to their stores – sunburnt fruit is unsaleable. Climate change theory suggests that average temperatures will increase and extreme weather events like heatwaves will become more frequent. To remain profitable, growers are being forced to protect against environmental factors such as increased heat, wind and hail,' Oakmoor Orchard’s Managing Director, Rocky Varapodio said.
An overhead evaporative cooling irrigation system has been developed by DEPI which involves the use of special low volume, misting sprinklers to apply small volumes of water at the tops of the trees during periods of high temperature. The water evaporates cooling both the surrounding air and the fruit. This is an effective way of reducing heat stress and sunburn by reducing the temperature of the skin of an apple by between 10–15 degrees after the first 20 minutes of application, with the core temperature (already lower) dropping by 5–7 degrees and staying cool for 1–2 hours after irrigation ceases.
The components of the low volume irrigation system are robust and designed for exposure to the elements. While routine maintenance is required, the equipment is durable and will easily have a lifespan of more than 10 years. Additional water is required, at an extra cost to the grower, however this is a very small cost compared to the value of the fruit.
In 2014 Oakmoor Orchards received a capital grant of $42,700 from Sustainability Victoria toward the cost of installing an evaporative cooling system over a 16.5 hectare trial block of Granny Smith trees.
'We had read about the technology and seen it demonstrated but to bite the bullet and spend a large amount of money on putting the technology onto the orchard was daunting and may not have happened without the funding grant,' said Rocky Varapodio. 'Having the grant meant that we shared the risk with Sustainability Victoria.'
Improving our resource efficiency has led to a significant reduction in waste and improved the bottom line of the Business.
Rocky Varapodio – Managing Director
The 16.5 hectare section of the orchard produces approximately 620 tonne of fruit, equating to $594,000 gross income. Without the evaporative cooling Oakmoor would expect losses due to heat stress of about 10% or around $59,000. With overhead sprinklers installed, Oakmoor estimated that sunburn loss was reduced from 10% to 2% i.e. an 80% reduction in loss, saving $47,000 per year. The pay-back period on the investment is less than 2 years.
The success of the trial means that Oakmoor will be rolling out the overhead evaporative cooling across other blocks of the orchard.
Oakmoor is also investigating hail netting to protect fruit from hail damage. It is also investigating the installation of solar panels on sheds and pumps to reduce energy costs.
Oakmoor's Rocky Varapodio had advice for other growers: 'As growers we are all operating in the same environment and there is lots of new technology out there that we can use or implement to get some efficiencies, I think that we all need to explore them as our industry becomes a lot more competitive'.
An overhead, evaporative cooling system reduced heat stress damage to apples by 80% saving $47,000 per year.
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