WITH the season from hell behind them, Sunraysia dried fruits growers are expecting a quality crop in 2012, but Dried Fruits Australia (DFA) is expecting little better than average yields.
The total yield for all varieties in last year’s rain and disease-ruined season was around 7000 tonnes, the lowest in decades. The previous season, also affected by rain, produced around 11,000 tonnes, well below Sunraysia’s potential production of around 17,000 tonnes.
DFA industry development officer John Hawtin said this week that SunMuscat and carina currants may be the exception, with some growers expecting to take off good crops.
But growers are not expecting a “monster crop” from the industry’s notoriously fickle mainstay, sultana, according to Mr Hawtin.
While bunches are large, with large berries, the bunches are sparsely distributed on the fruiting canes.
At the Nichols Point property of industry veteran Henry Tankard, a sparse sultana crop contrasts with his very healthy crop of promising new sultana-type variety SunGlo.
Mr Tankard is one of only two Sunraysia growers trialling SunGlo, which came out of the US Department of Agriculture’s dried fruits breeding program in California. Mr Tankard will harvest his fifth commercial crop from his regrafted former sultana vines in the coming season.
The variety is high-yielding and its berries have a waxier, more water-repellent coat than sultana, making it more resistant to splitting after rain – although Mr Tankard says even SunGlo split and suffered from botrytis mould in last year’s
relentless Big Wet.
The SunGlo vines are carrying a solid crop, as they have done every season since Mr Tankard top-worked a block of his aultanas to the new variety six years ago.
Sunglo’s fruiting nodes are closer together on their canes, and, unlike most sultana clones, every bud tends to produce a bunch. The denser, more even distribution of bunches along the rows contrasts with obvious gaps in the sultana rows.
Mr Tankard believes SunGlo will be an important complement to sultana as more growers take it up: it fruits later than sultana, and its resistance to splitting in the rain will allow growers to achieve a higher Brix reading before summer pruning and drying on the vine.
But the variety is not without risk. SunGlo matures later than sultana, and marginally later than the increasingly popular SunMuscat, another orphan USDA variety that failed to find favour among US growers because of its late maturity.
“All the emphasis in the USDA breeding program is on developing early-ripening varieties,” Mr Tankard said.
High Brix readings – a high concentration of sugar to moisture – mean a higher yield after drying, and greater profits.
But because SunGlo is already a late-maturing variety, the quest to maximise sugar content can push the drying period into late March or April, exposing the fruit to cooler days and nights; the berries can absorb moisture on nights with heavy dews, prolonging the drying process.
But Mr Tankard says one other positive for SunGlo is that it retains its golden colour during drying, even if affected by rain - unless rain has previously caused the ripe berries to split.
Another promising variety being trialled on several local properties is Bruce’s Sport, a mutant clone discovered on a Sunraysia property in the 1970s that bears prolifically and consistently from season to season.
Like SunGlo, Bruce’s Sport has proved to be highly resistant to darkening after rain, because of very low levels of the fruit-browning enzyme polyphenol oxidase (PPO).
Bruce’s Sport remained little more than a curiosity for at least two decades after its discovery, because it had accumulated a heavy load of plant viruses that compromised its vigour.
But in the 1990s, CSIRO researchers at the Merbein Horticultural Laboratory successfully cleansed the variety of viruses, by isolating tissue samples from the tips of rapidly growing shoots, and subjecting them to multiple rounds of tissue culture and heat treatment.
This article appeared in Saturday’s Sunraysia Daily 04/02/2012.
Email a friend