KIWI WINE TASTE CHANGES
SPARKED BY CLIMATE CHANGE
Increasingly the effects of climate change are being felt by winegrowers across New
Zealand, posing challenges for the industry which has boasted export earnings of $1.7
billion in 2018. This article from Nelson’s Wholesale Landscapes examines likely future
effects of climate change for viticulture and what mitigation strategies can be put in place.
TIMES ARE CHANGING: The past
four years have been the planet’s
hottest on record and increased
warming is expected going forward.
Climate change also brings the
increased frequency of erratic or
extreme weather events such as
droughts, heatwaves, damaging
wind, floods and unseasonal hail
storms, all of which can take a toll
on vineyards. Increased soil salinity
may also occur as a result of sea
level rise. Increased incidence of
pests and disease, such as powdery
mildew, can also result from warmer
average temperatures. Water
stress can reduce grape yield and
negatively affect fruit composition.
With lengthened growing seasons,
grape ripening is happening faster,
requiring earlier harvests and
potentially resulting in diminished
wine quality. Wine’s taste and
characteristics are affected by
weather variations which can
alter grapes’ sugar, acid and
tannin content, causing variation
from vintage to vintage. Higher
temperatures activate advanced
grape phenology, moving ripening
to warmer summer periods reducing
aroma compounds. High levels
of fermentable sugar concentrate
in grapes sooner, before complex
flavours develop, creating issues
for winegrowers aiming to balance
these against alcohol levels.
CLIMATE VS SCIENCE: New
Zealand’s favourite Sauvignon
Blanc, which makes up 85% of our
export sales, may risk losing its
distinctive flavour with increased
temperatures liable to promote a
flavour profile which is more mellow
tropical fruit than its current beloved
acidic gooseberry. Pinots grown
in cool climate areas now may
similarly suffer. Strategies to adapt
to climate change are required in
order to preserve wine’s original
style typicity.
Methods available to delay ripening
include altering plantation density,
limiting the height of vines and
utilising hail nets. Trimming shoots
or removing leaves to reduce the
leaf area to fruit weight ratio can
also help. Past Lincoln University
studies indicate management
techniques could also include
late pruning, canopy trimming or
the application of plant growth
regulators.
A FOCUS ON SOIL
SUSTAINABILITY: Increased
temperatures will mean soil
management practices will come
to the fore to better manage
grapevines’ water supply, control
vigour and avoid soil erosion,
as a European Winegrowers’
Guidance Manual advises. Planting
appropriate cover crops provides
ground shading and contributes to
humus formation which can buffer
very dry and very wet periods.
Employing less frequent tilling
and cultivation will also reduce
evapotranspiration.
The Manual further advises that
to minimise soil erosion and to
maximise nutrient and water
storage, mulching with plant fibres is
highly recommended. This practice
also increases organic matter under
the vine, limits the use of herbicides
and reduces soil evapo-transpiration
to avoid severe water stresses to
the grapevine during episodes of
drought. Mulching also prevents
nutrient leaching and increases the
efficacy of fertilisers, even during
rain events.
To offset the increase in pests
and diseases that climate change
may bring, consider implementing
integrated pest management, an
eco-system-based management
practice that integrates biological,
cultural, physical and chemical tools
to manage pests and diseases in
the vineyard.
THE FUTURE: Internationally,
some winegrowers are dramatically
relocating to cooler, higher altitude
areas, planting heat-resistant
varieties and increasing canopy
coverage to provide shade. One
Californian grower has embarked
on a project to breed a new grape
variety that is capable of being
dry farmed, (without irrigation)
and will withstand increased heat.
Research also indicates planting
on south-facing slopes to reduce
sun exposure, planting in shallow
soil to reduce water consumption
and introducing controlled or drip
irrigation are possible mitigation
strategies.
On the positive side, an increase in
40 FEBRUARY 2019