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Water and Irrigation
Grapevines lose lots of water by transpiration and evaporation during
their growing season since they have large canopies with big leaves
and there are large spaces between vines and rows. Developed grapevines, however, have large
root systems to absorb water from soil, so they can survive regions
with annual rainfall ranges from 270mm to over 1100mm (11 to 44
inches). For a mature
vineyard in Kentucky, irrigation is not extremely necessary even
under very dry conditions. Newly planted grapevines, however, do
not have well developed root systems and therefore need to be
watered frequently for the first couple of years. Also, vineyards
located on deep slopes or stony soils should think about
installing a irrigation system, although these sites should be avoided
at site selection.
Water is
held in the soil as films around soil particles and temporary in
pores so irrigation strategy should take soil characteristics into
account. For example, a sandy soil holds only about 1/3 of the water
that
clay or loam soil does.
Water
stress affects vine growth. Vines at different development stages
may handle different degrees of water stresses. Four phenological
intervals between budburst, flowering, veraison and harvest are
usually considered. Vines from budbreak to bloom are sensitive
to water stress, although in Kentucky it is not a problem since
enough rainfall usually takes place. During this time, however,
overhead sprinkling can help prevent frost damages; vines from
flowering to veraison can be subject to water stress since less
rainfall might happen and the water stress can lead to poor fruit
setting and small berries; vines from veraison to harvest can
withstand a considerable amount of water stress, which may also help
with sugar accumulation; after harvest, vines are usually ok without
irrigation unless extreme drought weather occurs.
Irrigation type: if irrigation is considered for a new vineyard,
water source, lines, control system and electrical requirements
should be considered during site preparation. I strongly recommend
an overhead sprinkling system for young vines, and more important, for
frost protection. It also can be used for reducing sunburn and
leaf temperatures during hot and dry seasons. Drip irrigation
is probably the most cost effective system for young vines (and old
vines), it can also be used for fertilization. For temporary
irrigation
(can be "permanent" for the first 2-3 years), T-tapes will be a very
good system, which is easy to set up, control and cost effective.
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Nutrition
The essential elements for vine growth and
development
When
an element is essential, it means
vines cannot finish their life cycle without it or a deficiency can be
disastrous. Potassium, nitrogen, calcium, magnesium, sulfur and
phosphorus are major elements (macronutrients) occurring at 0.2 to 3%
of dry weight; iron, manganese, molybdenum, copper, zinc and boron
are trace elements (micronutrients) occurring at 0.5 to 150 ppm (parts
per million). Some information on vine nutrition is listed in the
following table. Please note that the function of an element is
not provided.
|
Nutrient |
% of dry weight |
Amount per 1000kg grapes |
Deficiency symptom |
Range in petiole |
Application |
NOTE |
|
Nitrogen (N) |
1-2% |
2kg |
Reduced vigor: smaller leaves and
shoots, all-over yellowing leaves and other green tissues |
0.22-0.53 NO3 (%) or
500-1200 NO3-N mg/kg |
Young vines: apply 3g of actual
nitrogen per vine per month.
Mature vines: 20-60kg/ha before bloom annually. Can also
foliar spray 5g urea/litre. |
Increase in vigor: reduction in fruit set and bud fertility; reduce cold hardiness |
|
Phosphorus (P) |
0.1-0.3% |
0.6kg |
A gradual reduction in shoot growth. Basal leaves may pale
or turn yellow and fall before flowering. |
0.2-0.46 P (%) |
Preplanting: deep place 0.5-1.0 tonne superphosphate/ha.
Mature vines: apply 0.5-1.0 tonne superphosphate/ha once
every 3 years. |
Phosphorus is relatively immobile in the field. Applying to
the root zone will help. |
|
Potassium (K) |
up to 3% |
5kg |
Symptom shows first in the older
leaves. Older leaves of white variety become yellow
near the margin and this chlorosis extends inwards the
center of leaf, can become acute marginal burning. Red
cultivars show red rather than yellow coloring prior to the
marginal burning. Bunches are small and tight, berries ripen
unevenly. |
>1.5 (%)
<0.5% deficiency |
Can add 1-2 tonne/ha into planting lines before
planting; When needed, young vines 40g/vine/month; old
vines, 1-2 tonne/ha of K2SO4. Foliar
spray of KNO3 at 10-20g/L can be used. |
High K in juice affects wine quality since it increases pH.
For N,P,K addition, the cheapest
mixed fertilizer can be used, e.g., 14-14-14 lawn
fertilizer. |
|
Magnesium (Mg) |
50-150 ppm |
|
Yellowing between veins of older
leaves; red cultivar shows a red pigmentation in
these vein areas. |
>0.3% |
Use dolomitic limestone (9% Mg) in acid soils or add
magnesium sulfate (19% Mg) to soil or foliar spray (20g/L) |
|
|
Iron (Fe) |
50-150 ppm |
|
A diffuse yellowing of young leaves
and new growth, veins may remain green if deficiency not so
acute. |
|
Not easy to correct since the form of Fe2+ is the active
form in plants. Apply iron sulfate or some iron chelates.
Foliar spray can be used. |
Lime soil causes Fe deficiency, especially for cultivars of
Concord blood. |
|
Manganese (Mn) |
50-150 ppm |
|
A yellowing occurs between the main veins in broad bands on
older leaves. |
>25ppm |
Foliar spray of 1.5 g/L manganese sulfate |
Some fungicides (Mancozeb) contain Manganese |
|
Zinc (Zn) |
0.5-40ppm |
|
"little leaf" symptom and stunted growth: the small leaves
have a detailed mottling between the veins and have a
widened petioar sinus where the leaf stalk connects to the
leaf. |
>26 |
Foliar sprays of zinc oxide (2g/L) or zinc sulfate (1g/L). |
Some fungicides (Mancozeb) contain Zinc. |
|
Boron (B) |
0.5-40ppm |
|
Reduced fruit set, more seedless berries; death of shoot
tips and yellowing between veins of recently matured leaves |
30-100ppm |
Foliar spray before bloom (3b/L). |
|
|
Copper (Cu) |
0.5-40ppm |
|
Not usually seen since copper containing sprays usually take
place. |
>6 ppm |
|
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Determining the need of Fertilization
Analyze your soil: Soil
samples should be collected before planting. Contact your county
extension agent for more information.
Tissue analysis:
Petioles and blades have been used
to represent the nutrition status of vines. California grape
growers use petioles while the Australian use blades. Petioles
can be sampled at two different times during the growing season.
Bloom-time petioles are the best indicators of zinc and boron
status, while sampling at veraison will provide more accurate
readings of potassium and magnesium levels. But practically,
only do sampling at full bloom (70%
capfall) for petiole analysis. If you want to do blade samples,
the veraison stage will be the best
time. When sampling, collect about 100
petioles or blades from basal
leaves opposite to bunches, early in the morning; dry
them at room temperatures or store them in the refrigerator
before mailing them to the laboratory. Different cultivars
should be separated.
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