WSET LEVEL 4 DIPLOMA D1
EXAM Questions and Answers Latest
Versions 2025 GRADED A+
what could cause low carb levels in roots, trunk, and branches?
- excessive leaf removal
- water stress
- mildew
- high crop loads in prev season
what can slow initial shoot growth rates?
low carb levels
what supports shoot growth in later stages?
photosynthesis
at what point of the vine growing cycle is water stress not desired?
late stages of shoot growth (can affect photosynthesis)
what can stunted shoot growth lead to?
- weak shoots
- reduction in leaf number/smaller leaves
- inflorescences that do not flower properly
what can limit bud fruitfulness?
- low temp (<25C)
- water stress
- shading
- nutrient deficiency
how long after budburst does flowering typically take place?
8 weeks (temp dependent)
why are warm conditions (>17C) desired during flowering?
speeds up flowering (occurs within a few days)
what % of flowers become grapes typically?
30%
,what temp does pollen germination require?
26-32C
what negatively affects pollen tube growth?
wind, rain, cold temps; wind, water stress, hot temps
define coulure
A condition of the grape bunch in which fruit set has failed for a high proportion of flowers. This occurs
when ovule fertilisation is unsuccessful, and therefore no grape develops.
what causes coulure?
imbalance in carb levels due to:
- low photosynthesis rates
- vigorous shoot growth diverting carbs (very fertile soils, vigorous rootstocks)
define millerandange
A condition of the grape bunch in which there is a high proportion of seedless grapes.
what causes millerandange?
cold, wet, windy weather at pollination and fruit set
what elements develop in grapes during stage 1 of grape formation and development?
- tartaric and malic
- some aroma compounds and aroma precursors (methoxypyrazines)
- tannins (promoted by sunshine on grapes - sunscreen)
during stage 1 of grape formation and development sugar levels are , water flow is &
provided by the .
- low
- high
- xylem
too much & can prolong stage 1 of grape formation and development because
. this can delay .
- water
- nitrogen
- these will encourage shoot growth instead
- onset of the ripening stage
During stage 1 of grape formation and development, mild water stress can and
lead to the production of grapes.
- speed up this stage
- smaller
shoot growth during stage 1 of grape formation and development.
continues but slows
, what is stage 2 of grape formation and development?
veraison (transition between grape growth and grape ripening)
what is the lag phase?
grape growth slows for a few days during veraison
describe what happens during veraison
- skins become more elastic
- green chlorophyll is broken down
- anthocyanins are synthesized
describe the process of grape growth and ripening
1. phase 1: grape growth: cell division and expansion
2. tartaric acid accumulation
3. malic acid accumulation
4. lag phase (phase 1 ends, phase 2 begins)
5. malic acid degradation
6. hexose sugar accumulation (development of xylem cell discontinuities -> lower V of water entering
accounts for about 75% of this, other 25% from sugar development via photosynthesis)
7. degradation of methoxypyrazines
8. chlorophyll breakdown; carotenoids (white grapes), anthocyanins and xanthophylls (red grapes)
develop
what is stage 3 of grape growth and ripening?
ripening
what happens during grape ripening?
- cells expand rapidly
- sugar and water accumulate
- acid levels fall (respiration of malic acid)
at what temp does photosynthesis take place at a max rate? at what sunlight levels?
- 18-33C
- >1/3 full sunshine
where does sugar come from during ripening?
- sugar solution from phloem (sugars from photosynthesis)
- reduction in water (xylem flow stops, water is transpired through grape skins)
Mean temperatures above in the final month of ripening can lead to a rapid loss of
acidity
21C (70F)
mean temperatures below can reduce acid loss to a point that acidity levels in the must
are too high
EXAM Questions and Answers Latest
Versions 2025 GRADED A+
what could cause low carb levels in roots, trunk, and branches?
- excessive leaf removal
- water stress
- mildew
- high crop loads in prev season
what can slow initial shoot growth rates?
low carb levels
what supports shoot growth in later stages?
photosynthesis
at what point of the vine growing cycle is water stress not desired?
late stages of shoot growth (can affect photosynthesis)
what can stunted shoot growth lead to?
- weak shoots
- reduction in leaf number/smaller leaves
- inflorescences that do not flower properly
what can limit bud fruitfulness?
- low temp (<25C)
- water stress
- shading
- nutrient deficiency
how long after budburst does flowering typically take place?
8 weeks (temp dependent)
why are warm conditions (>17C) desired during flowering?
speeds up flowering (occurs within a few days)
what % of flowers become grapes typically?
30%
,what temp does pollen germination require?
26-32C
what negatively affects pollen tube growth?
wind, rain, cold temps; wind, water stress, hot temps
define coulure
A condition of the grape bunch in which fruit set has failed for a high proportion of flowers. This occurs
when ovule fertilisation is unsuccessful, and therefore no grape develops.
what causes coulure?
imbalance in carb levels due to:
- low photosynthesis rates
- vigorous shoot growth diverting carbs (very fertile soils, vigorous rootstocks)
define millerandange
A condition of the grape bunch in which there is a high proportion of seedless grapes.
what causes millerandange?
cold, wet, windy weather at pollination and fruit set
what elements develop in grapes during stage 1 of grape formation and development?
- tartaric and malic
- some aroma compounds and aroma precursors (methoxypyrazines)
- tannins (promoted by sunshine on grapes - sunscreen)
during stage 1 of grape formation and development sugar levels are , water flow is &
provided by the .
- low
- high
- xylem
too much & can prolong stage 1 of grape formation and development because
. this can delay .
- water
- nitrogen
- these will encourage shoot growth instead
- onset of the ripening stage
During stage 1 of grape formation and development, mild water stress can and
lead to the production of grapes.
- speed up this stage
- smaller
shoot growth during stage 1 of grape formation and development.
continues but slows
, what is stage 2 of grape formation and development?
veraison (transition between grape growth and grape ripening)
what is the lag phase?
grape growth slows for a few days during veraison
describe what happens during veraison
- skins become more elastic
- green chlorophyll is broken down
- anthocyanins are synthesized
describe the process of grape growth and ripening
1. phase 1: grape growth: cell division and expansion
2. tartaric acid accumulation
3. malic acid accumulation
4. lag phase (phase 1 ends, phase 2 begins)
5. malic acid degradation
6. hexose sugar accumulation (development of xylem cell discontinuities -> lower V of water entering
accounts for about 75% of this, other 25% from sugar development via photosynthesis)
7. degradation of methoxypyrazines
8. chlorophyll breakdown; carotenoids (white grapes), anthocyanins and xanthophylls (red grapes)
develop
what is stage 3 of grape growth and ripening?
ripening
what happens during grape ripening?
- cells expand rapidly
- sugar and water accumulate
- acid levels fall (respiration of malic acid)
at what temp does photosynthesis take place at a max rate? at what sunlight levels?
- 18-33C
- >1/3 full sunshine
where does sugar come from during ripening?
- sugar solution from phloem (sugars from photosynthesis)
- reduction in water (xylem flow stops, water is transpired through grape skins)
Mean temperatures above in the final month of ripening can lead to a rapid loss of
acidity
21C (70F)
mean temperatures below can reduce acid loss to a point that acidity levels in the must
are too high
