Water management – Controlling
canopy growth by regulating water to
achieve yield and quality goals is fundamental
to winegrape production. If
sunburn and/or heat damage regularly
causes crop loss, then working
to better understand water relations
for canopy management purposes in
those blocks can benefit fruit quality.
Regularly monitoring both soil and
vine water status will allow growers
to see the effects of applied water and
soil water disappearance on specific
objectives for shoot growth, berry size,
Knowing the relative amount
of water vines can extract in high
evaporative demand conditions and
how quickly that moisture can disappear,
will allow you to apply the right
amount at the right time to minimize
vine stress. Applying water each day
of a heat spell will not reduce vine
water stress if soil moisture content
was too low before starting.
Leaf removal – In a region with high
winter rainfall, controlling early season
vine growth is accomplished by
withholding irrigation until shoot
growth slows, and by utilizing cover
crops to deplete stored soil moisture.
Shoot thinning is required to maintain
desirable spur positions and manage
crop load. In most sites, those
practices alone do not result in the
desired level of fruit exposure; however
in low vigor sites they may.
The quantity and quality of light
on clusters and the timing of exposure
has significant effects on fruit
composition. The goal is to create
a light environment in the canopy
that achieves fruit quality targets yet
avoids excessive heating of clusters.
If a site frequently experiences sunburn
or heat damage, then the severity
of leaf removal must be reduced to
In cool, foggy regions, leaf removal is
essential for disease control and for fruit
exposure, as dense canopies are common
due to high soil moisture. Because
hot periods are more infrequent than in
warmer regions but not absent, determining
optimal cluster exposure is
more challenging in these regions.
Sprinkler cooling – Utilizing sprinklers
for evaporative cooling is an option
for some growers. When weather forecasts
predict expected high ambient
temperatures around 100°F or greater,
sprinklers — either traditional impact
or targeted systems — can be used to
achieve evaporative cooling.
Most research with over-vine sprinklers
to achieve cooling has been conducted
with impact sprinklers, which
provide total vineyard floor coverage.
Over-vine targeted sprinklers and
under- or over-vine micro-sprinklers,
misters, etc. have also been used to
provide cooling with reduced water
use. Temperature sensors
blocks allow determination
of when temperatures stabilize after
turning on sprinklers, and help growers
meet water conservation goals.
Sprinkler irrigation time required
to reduce and stabilize vineyard temperatures
may be surprisingly short,
at which point there is no further
temperature drop by maintaining
overhead cooling. After the system
is turned off, the cooling effect will
continue as water evaporates off vine
surfaces. The duration of this effect
can be measured by temperature sensors
in the vineyard block.
1. Dokoozlian, N. 2009. Foundations of
canopy management: the contributions
of Dr. Mark Kliewer. In Proceedings for
the Recent Advances in Grapevine Canopy
Management, International Symposium. N.
Dokoozlian and J. Wolpert (organizers),
pp. 43-52. University of California, Davis.
2. Mullins, M.G., A. Bouquet, and L.E.
Williams. 1992. Biology of the Grapevine.
Cambridge University Press, Cambridge,
3. Williams, L.E., and P. Baeza. 2007.
“Relationships among ambient temperature
and vapor pressure deficit and stem
and leaf water potentials of fully irrigated,
field-grown grapevines.” Am. J. Enol. &
Vitic. 58: 173-181.