Home' Cherry Magazine : Cherry winter 2017 Contents Winter 2017 | horticulture.com.au/grower-focus/cherry
10 WA CHILL
Research is helping growers adapt to changing temperature conditions.
Reduced winter chilling is an issue
likely to be faced by growers across all of
Australia’s major growing regions. In 2012,
an industry report found that global warming
was expected to reach 2oC by 2040,
which would “negatively affect reliable chill
exposure” throughout the industry. This
could potentially lead to sporadic and light
budbreak, poor fruit development, small fruit
size and uneven ripening times.
What management tools and practices
can growers use in such a situation to
ensure the ongoing profitability of their
business? Overseas researchers and
growers, including those in the US and
other countries who face similar challenges,
are exploring several approaches. These
include the use of low-chill varieties,
specific rootstocks and dormancy breakers.
Obviously, reliable information about
varietal performance and the outcomes of
management practices is critical to guide
This is easier said than done because
there are so many unknowns and
complexities involved. A recent Australian
Government-sponsored project – Crossing
the threshold: Adaptation tipping points for
Australian fruit trees – found that the chilling
requirements for a single cherry cultivar
(Lapins) varied according to geographic
location, which is at odds with assumptions
of fixed cultivar chilling requirements.
In Victoria, cherry grower Steve
Chapman says while the Yarra Valley
is predicted only to be affected under
“extreme change” scenarios, it is reassuring
for growers to know that researchers are
working on the problem.
“It is not simple any more. Certain
varieties struggle to set crops in some
areas, so it is about knowing what you are
doing and which varieties are affected. It
definitely helps to have research backing us
up with data so that growers can make the
right decisions,” he says.
One of the largest growers in WA,
George and Kathy Grozotis of Cherry
Lane Fields in Manjimup, say they have
been forced to adapt by the changing
circumstances caused by climate change.
The third-generation growers have about
10,000 trees, with the main varieties being
Lapins, Sweet Georgia, Simone, Sonata and
Sweetheart, producing between 55 and 70
tonnes of fruit a year.
“Climate change has meant that we’ve
had to introduce new varieties that suit the
warmer weather, even though the Southern
Forests region is still perfectly suited for
cherry production and they do taste better
down here,” Mr Grozotis says.
“Over the past eight years, we have
been getting warmer winter temperatures.
These high temperatures during winter
can alter the length of our dormant period.
Inadequate chilling can cause delayed and
prolonged budburst, resulting in uneven
flowering and fruit maturity. Flowers are
substantially reduced and/or are shed. This
was the case for three years in a row – 2011
to 2013 – resulting in low yields.
“In the past five years, each winter we
have been experimenting with plantings of
different cherry varieties that require lower
chill, but still produce a cherry of quality
that is suited to the marketplace. Similarly,
each year we are removing varieties that
are failing to produce. This year we are
contemplating removing Bing. In the last
five years the yield from Bing has not been
economically viable.” (Bing is at the top of
the scale for chill hours required.)
Balingup, WA, farmer Ron Robertson
agrees, saying that new low-chill varieties
are the best way forward to adapt to a
Simone cherries ready for picking.
PHOTO: COURTESY CHERRY LANE FIELDS
BY IAN LEWIS
cherry growers are
endowed with huge
opportunities but also
face big challenges,
particularly in the face of global warming
and less winter chilling.
WA is a low-chill region compared to
south-eastern Australia. “Accumulation of
winter chill is required to break dormancy,
which allows trees to resume growth in
spring and to flower and subsequently fruit,”
says Susie Murphy-White of Pomewest.
“Because WA is getting less winter chill,
fruit trees are flowering longer; in some cases
flowering takes about a month, compared
to potential same-day flowering of trees in
Tasmania. Less chill results in fruit maturity
being delayed, fruit quality being affected and
repeated fruit picks based on the varied times
of flowering on the same tree.”
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