Hazard, Pests and Diseases 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?
500mm per year in cool climates
750mm in warm climates
What happens when vines do not get enough water?
- Vines will close the stomata on their leaves to limit water loss.
- Photosynthesis reduces
- Slows growth and ripening
- Reduces grape size
- Lower yields, unripe grapes
- Leaf loss, death
What are three management options for drought?
- Irrigation systems
- Drought-resistant rootstock (140R / 110R)
- Drought-tolerant varieties (Garnacha)
What hazards are associated with excess water?
- Too much vegetative growth = Competition with grape ripening
+ Fruit is too shaded
+Less ripeness - High humidity = Fungal Disease
- Poor drainage, 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 an excess of water.
- planting on a slope
- planting on free-draining soil
- construction of a drainage system
What problems are associated with excess rainfall during pollination and fruit set?
- Millerandage or coulure
- Reducing the size of the crop
- Potentially lowering quality
Name three problems associated with heavy rainfall close to harvest.
- 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)
At what low temperature can the vine can be seriously damaged or even killed by winter freeze?
−20°C / −4°F
Which parts of the vine are most at risk from winter freeze?
- Graft
- Cordon / Canes
What climate type is most affected by winter freeze?
Continental climates e.g. Canada, China
what are three general management options for freeze?
- Site selection:
- hillsides (+5C from valley floor)
- proximity to large bodies of water
- planting where snow settles most thickly - Choice of varieties
- Cabernet Franc / Riesling - ## Protecting vines
Name three methods of protecting vines from freeze.
- Hilling Up” - Building up soil around the vine graft as the soil underground is only a few degrees below freezing.
- Burying vines - Very costly approach as it requires a lot of labour every year (China)
- Vines can also be pruned to have several trunks so that those killed in winter can be replaced.
Name and describe two types of frosts.
- Advective frosts = Large volumes of cold air moving from cold areas to warm areas.
- Radiative frosts = Result of heat being lost on still, cool nights.
- The earth is heated by the sun during the day and releases it during the night.
- The amount of heat lost depends on the level of cloud cover.
- Windless nights allow a layer of freezing cold air to develop just above the surface of the soil.
- Cold air is denser than warm air, this freezing cold air will collect in valley bottoms.
List five actions that can be taken to reduce the risk/impact of a frost event.
- In site selection, care must be taken to avoid frost pockets.
- Delaying pruning postpones budburst into warmer months.
- Choosing a variety that buds late, such as Riesling.
- Vines trained high off the ground
- Having bare soil between the vines
List and describe three systems for fighting frosts in the event.
- Water sprinklers (also known as aspersion) = - As water freezes around the parts of the plant, it releases latent heat, protecting the plant
- Wind machines = Large fans, 4-7 m high, pull warmer air from above down to ground level, thereby raising the temperature.
- Oil or propane gas burning heaters and wax candles = Heat the air in the vineyards around the vines.
