Hazards Flashcards
Name the 9 main hazards.
- drought
- excess of water
- untimely rainfall
- freeze
- frosts
- hail
- sunburn
- fire
- smoke taint
What is the minimum amount of water vines need per year in cool climates?
500mm per year
What is the minimum amount of water vines need per year in warm climates?
750mm per year
What happens when vines do not get enough water?
- vine will close the stomata on their leaves to limit water loss
- reduces photosynthesis
- slows growth and ripening
- reduces grape size
- lower yields, unripe grapes
- leaf loss, death
What are management options for drought?
- irrigation systems
- drought-resistant rootstock
- drought-tolerant varieties
What is a drought-tolerant variety?
Garnacha
What is a drought-resistant rootstock?
Rootstocks from V. rupestris and V. berlandieri parentage (e.g. 11R and 140R)
What are hazards associated with excess water?
- too much vegetative growth
- high humidity
- poor drainage, waterlogging
What are problems associated with vegetative growth?
- competition with grape ripening
- fruit is too shaded
- less ripeness
What is a problem associated with high humidity?
Fungal disease
What are problems associated with poor drainage and waterlogging?
- prohibits oxygen from getting to the roots
- slows growth
- can kill the vine
- difficult to work/uncontrollable water run-off
Name some management options for excess of water
- planting on a slope
- planting on free-draining soil
- construction of a drainage system
What are problems associated with excess rainfall during pollination and fruit set?
- millerandage or coulure
- reducing the size of the crop
- potentially lowering quality
What are problems associated with excess rainfall during the mid-season?
- can reduce the rate of ripening of fruit
- mild water deficiency before veraison reduces the growth of shoot tips, allowing the grapes to ripen more satisfactorily
What are problems associated with heavy rainfall close to the vintage?
- grapes swollen with water (reducing the concentration of the must and with it the quality of wine
- grapes splitting (grey rot)
- makes harvest very difficult (difficulty using mechanical harvesters, accessing the vineyard if on clay soils
What are management option for untimely rainfall?
Mitigation:
- choice of site (climate in general, slope)
- condition of the soil
- adequacy of drainage
- monitoring weather forecasts (early harvest)