Transcript Introduction to Viticulture

Introduction to
Viticulture
Vineyard Site
Selection
I. Introduction
• A. The first consideration for successful
investment in a new vineyard is the
selection of an outstanding site.
• B. This strategic and critical step will
condition all the future performance of the
vineyard not only in the years of
establishment, but also for the rest of the
more than 20 years of the expected
vineyard life.
• C. Essential to success in any vineyard is
a favorable combination of locality, variety
of grapes, and proper utilization of the
crop:
– Riesling wines of Germany
– Ohanez grapes of Spain
– Thompson Seedless raisins of California
• Cannot be easily duplicated in any other
part of the world.
• D. It may be assumed that only a region meeting
the general requirements would be under
consideration. (Lecture # 4)
• E. One must then make a study of the region in
order to choose the district best suited to the
class of grape to be grown.
• F. If one already has a tract of land, study of
conditions is required to determine the type of
grape that can successfully be grown.
• G. If grapes are already being grown in the
district, the necessary information can
probably be gained by observing the
success of the local industry and the
difficulties encountered, and then
comparing these with similar observations
made in other districts.
II. Important Factors to Consider
•
•
•
•
•
•
A. Topography
B. Climate
C. Soil
D. Neighboring Land
E. Potential Pest and Threats
F. Non-environmental Factors
III. Topography
• A. Elevation
– 1. Elevation is a factor known to dramatically
influence the climate of a site.
– 2. With every 150 feet gain in elevation the
average temperature decreases 1 degree F.
– 3. Viticulture areas in Missouri range from 300
to 1300 feet.
– 4. Elevation has a profound influence on the
minimum and maximum temperatures in a
vineyard, particularly hilly terrain.
– 5. Because frosts and freezing temperatures
can dramatically reduce vineyard profitability,
elevation is one of the most important
features of vineyard site suitability.
– 6. The physics of topography effects on air
temperature are well documented.
• A. Under radiational cooling conditions, with calm
winds and clear skies, the earth loses heat to
space and cools the adjacent layer of air.
• B. If the vineyard is on a slope, the cold, relatively
dense air moved downhill.
• C. This movement can be pronounced in hilly
areas.
• D. The sinking, cold air displaces warmer air to
higher elevations producing thermal inversions and
thermal belts.
• E. Above these relatively warm belts, air
temperature again decreases at an average rate of
3.6 degrees F/1000 feet of increase in elevation.
• F. The sinking, cold air collects in low-lying areas
and can create frost pockets.
• G. A very high percent of spring freezes are cause
by radiational freeze situations.
• H. Vineyards in low-lying frost pockets are much
more prone to spring and fall frost damage and
winter cold injury, than are vineyards that have
been established at higher elevations.
• I. A combination of local experience and research
can be used to define the upper and lower limits of
the desired thermal belt or zone for the hill/valley
region.
• B. Slope
– 1. Slope is the inclination or declination that a
parcel of land varies from the horizontal,
usually expresses as a percentage.
• A. A five foot drop over a 100 feet horizontal
distance would be a 5% slope.
• B. Perfectly flat land would have a 0% slope.
• C. A vertical cliff would have a 100% slope.
– 2. Slope can be accurately measured with an
inexpensive, handheld inclinometer.
– 3. A slight to moderate slope is desirable
because it accelerates the drainage of cold air
away from the vineyard. Cold air is denser
than warm air and tends to flow downhill,
much like a fluid.
– 4. Generally, the steeper the slope, the more
pronounced the temperature differential with
changes in elevation.
– 5. Cold air also tends to moves downhill faster
on steeper slopes.
– 6. Water also drains more quickly down steep
slopes.
• A. Pro – Good Drainage; No Waterlogging.
• B. Con – Erosion!!
– 7. It is dangerous to operate equipment on
slopes steeper than 15%.
• Terracing of slopes is possible but will add
significantly to the cost of vineyard establishment.
• C. Aspect
– 1. Aspect of the slope refers to the prevailing
compass direction which the slope faces
(east, southeast, etc.)
– 2. Aspect will affect the angle that sunlight hits
the vineyard and thus the total heat balance
IV. Climate
• A. Temperature
– Vines’ Genetic Limitations
Length of Growing Season in
Missouri
Length of Growing Season in
Eastern Missouri
•
•
•
•
175
180
185
190
Length of Growing Season
• <150
• 150-160
• 160-170
• 170-180
• > 180
• > 200
American, Early Maturing
French-hybrid
American, Several Early
Hybrids
Early Maturing Viniferas,
French hybrids
Vinifera & Hybrids
Most Viniferas
Late maturing Viniferas
– Spring Frost Damage
• Fluctuating temperatures are a big problem with
fruit production in Missouri.
• Fruit buds freeze at 28 degrees F.
• Is influenced by growing season length
• Is influenced by topography
• Is influenced by adjacent vegetation
• Windbreaks/air drainage
• Stage of plant development
– Air Temperature Influences Rate of
Photosynthesis/Rate of Respiration
•
•
•
•
•
•
Yield
Growth
Fruit Quality
Flower Initiation
Bloom
Fruit Set/Growth/Development
Cold Winter Injury
– 1. Assessing Cold Injury of Grape Buds
• A. Choose buds similar to those you will save
during pruning. This means the lower nodes of the
canes of the better quality on the vines.
• B. Sample based upon differences in you vineyard.
This can be by variety, rootstock or based upon
site and soil differences (lower vs upper sections,
better or less well drained etc.)
• C. Collect at least 100 nodes from each section.
• D. If the freeze was recent and the buds may not
have thawed since exposure to potentially harmful
temperatures, then bring the warm canes into a
warm room, keep the canes moist and wait for 2448 hours before examining the buds. This allows
the damaged cells to thaw and the oxidative
reactions which reveal damage to happen.
• E. Cut the buds and record the number of live and
dead primary buds.
• F. You can also record the status of the secondary
and tertiary buds. This is worthwhile information
but not as important as primary bud survival.
Longitudinal Section of a Grape Bud
(note the three growing points or buds)
This is the region of the bud which should be
examined to assess primary bud injury. The
colored area is the compresses primary shoot for
the next season.
This is the region of the bud which should be
examined to assess secondary bud injury. It is
adjacent to the leaf scar.
This is the region of the bud to examine to assess
damage to the potential tertiary shoot.
The Examination
• On the left is an intact grape bud. The leaf scar is to the
left. The bulge on the left side of the bud is the
secondary bud. The right picture shows a longitudinal
view. In the series below the top view of a bud having
successive horizontal slices removed is shown (click on
the thumbnails to see the bigger picture). The line on the
right shows the approximate level of the horizontal cut.
Intact bud
First cut. This is too shallow only the tips of the bud
scales have been cut. The secondary bud is just
beginning to be revealed at the lower left quadrant
of the cut.
Second cut. This cut is still too shallow. The
secondary bud is better defined, but only the tips
of bud scales have been cut.
Third cut This cut shows a life primary bud. The cut
has been through what will become a shoot
internode. People often worry about whether the
color is bright green, olive green or sort of gray.
Just so long as the bud is not blackened, it is alive.
• The tertiary bud can now be seen, but only bud
scales of the secondary and tertiary buds have
been cut.
Fourth cut
• This is a good level to assess the health of the
secondary and teritary buds, but it is too deep to assess
primary bud health. Once the cut moves to the base of
the shoot (the bud cushion), the status cannot be
assessed. Dead buds will often be found on live bud
cushions.
Fifth Cut
• This cut is too deep. Only bud cushion is
revealed. There may be dead primary,
secondary and tertiary buds on top of a live bud
cushion. Deep cuts may give a false sense of
security.
The primary bud of this bud has died. The
secondary bud is alive. The tertiary bud cannot be
evaluated at this level of cut.
• The above series shows why a single cut will not
reveal the complete status of the buds nor even
allow certainty as to the status of the primary
bud. A series of shallow cuts is recommended.
• 2. Responding to Winter Cold Injury to
Grapevine Buds
– There are three ways to deal with cold:
• A. Avoid the cold stress
•
1. Find a warm place to grow grapes this is site selection
•
2. Protect the buds or tissues from
exposure to cold by burial or other means.
B. Tolerate the cold
•
1. Grow a variety with sufficient cold
hardiness to tolerate the expected temperatures.
•
2. Maximize the maturity of the tissues
you grow by applying excellent viticulture.
• 3. Tolerate the cold injury
–A. If all the above ground vine tissues
are killed, there is little you can do
except replant or retrain from below the
ground, but partial vine death is much
more common.
–B. Delay pruning as long as feasible so that the
danger of cold injury is reduced. (If December,
January and February have passed without
extreme cold, the danger is reduced. March
may still produce damaging temperatures, but
your odds of avoiding injury have increased.)
–C. If you suspect possible cold damage,
examine the buds and proceed on the basis of
actual injury.
• 3. Compensating for bud injury
– A. If you know buds have been injured, you
can retain more to compensate for the
proportion of dead buds. Remember even
when there is no cold damage, it is not
uncommon for 10% or more of the buds not to
develop.
– B. % dead primary buds
– Compensation
• 0 – 20
• Do not change normal
pruning practice
• 20 - 80%
• Increase the number of
buds retained in
proportion to the injury
• >80%
• Prune away only those
nodes which will intrude
into the space of adjacent
vines or which will
produce fruit so low that it
hangs to the ground
Cane Damage (right cane has
suffered from cold damage)
• B. Spring Freeze Damage
– 1. Is best controlled by site selection
– 2. Can also be controlled (to some extent by)
•
•
•
•
A. Heaters
B. Overhead Sprinklers
C. Evaporative Cooling
D. Chemical Applications
• Heaters
– High Fuel Cost
– Operation logistics
– Energy-efficiency
– Air Pollution
• Overhead Sprinklers
– Does not rely on
inversion
– Initial investment and
operating cost per
acre are cheater than
heaters
– No extensive labor to
operate
– Clean and Quiet
– Fuel efficient
– Waste Water
– Water logging of soil
possible
– Nutrient leaching
– Application rate is
critical
– Separate installation
for irrigation and frost
protection
• Evaporative Cooling
– Preventative or passive protection method
since the sprinkler system is turned on well
before a spring frost event.
– Although this method has been successful in
delaying bud break of grapevines, evidence of
protecting crop from frost injury is uncertain.
• Chemical Application
– Claimed to provide freeze protection and
prevent crop damage by unknown mode of
action.
– Inconsistent results over the last five decades
have discourages widespread use
– Growers should beware about believing the
promotional claims of these materials.
• Grape Plant Chilling Requirements
– Vinifera
– Labrusca
100-400 chilling hours
1200-1500 chilling hours
Temperatures most effective in meeting the
chilling requirements of plants are between
37-50, with most commonly accepted
between 32-45. Temperatures above 59 will
reverse the chilling process.
• B. Rainfall
– Rain provides needed water for grape growth.
– On average, annual rainfall in the
Southeastern part is Missouri averages 50
inches per year.
– Mature grape vines can use 24-30 inches of
rainfall per year.
– But Missouri summer precipitation occurs in
thunderstorms quite often.
– Erratic rainfall distribution, often coupled with
soil of low water infiltration rates and/or
shallow soil with low water holding capacity,
can lead to water stress for grapes.
– Supplemental irrigation is a useful tool for
optimizing yields and quality.
• Macro-, Meso-, and Micro-Climate
– Macro-Climate – Missouri or even Mid-west
averages.
– Meso-Climate – A single field or hill side.
Influenced by aspect, slope, elevation,
barriers to air drainage.
– Micro-Climate – The environment beneath the
grape canopy. Influenced by humidity, shade
and air movement.
V. Soil
•
•
•
•
•
•
Organic Matter
Water Holding Capacity
Depth
Erosion
pH
Micro-organisms
• Soil Organic Matter
– Plant and animal residue in various stages of
decay
– Improve the physical and chemical condition
of the soil
– A source of nutrients for micro-organisms
– A source of plant nutrients
• Micro-organisms
– Improve soil structure
– Improves root penetration
– Facilitates water entrance and percolation
– Increases water-holding capacity
– Improves drainage
• Soil Compaction
– Soil Texture
• Soil Drainage
– Well drained soils have uniformly bright colors such
as brown, yellow, red or combinations of these colors.
The surface may be darkened by organic matter.
– Uniform light gray colors in the profile indicate
prolonged saturation with water.
– Surface light gray soils, water stands on surface for
prolonged periods in summer.
– Mottled or bright brown, yellow intermixed with gray
spots the soil is saturated.
• Internal Soil Drainage (If poor)
– Reduced accessibility by equipment
– Small vine size
– Reduced productivity
– Increased hazard of winter injury
• Root Depth
– Capable of rooting to a depth of more than 20
feet.
– Typically are concentrated in the upper 36”
– Sometimes even in the upper 18”
• Soil Chemistry
– Nutrients in the soil are most available for
uptake when the soil is relatively neutral
(ph=7.0)
– A comprehensive soil test including
micronutrients should be evaluated.
VI. Neighboring Land
• Wildlife
–
–
–
–
Deer
Birds (including wild turkey)
Raccoons (especially in irrigated vineyards)
Opossums
• Phenoxy Herbicides
– Broadleaf weed killers (2,4-D) used in corn field will
cause dramatic injury to grapes.
– 2,4-D can travel in humid, windy conditions for
several miles.
VII. Potential Pest and Threats
• Diseases
– Pierce’s
Disease
VII. Potential Pest and Threats
North American
Grapevine Yellows
Black Walnut Toxins
VIII. Non-environmental Factors
•
•
•
•
•
Proximity to Market
Reputation of Region
Availability of Labor Force
Availability of Services (water/power)
Accessibility by road (trucks/tourist)
IX. Viticulture Suitability Ranking
•
•
•
•
Elevation
Slope
Land Use
Aspect
35 points
35 points
20 points
10 points