Hazards, Pests and Diseases

Question 1

Advective Frost

Answer 1

Occurs when large volumes of cold air move in from very cold areas.

Question 2

Radiative Frost

Answer 2

Soil is heated during the day and released at night. On cold, still nights. Freezing cold air develops above the soil surface. Cold air sinks and settles on valley floors.

Question 3

Frost Management

Answer 3

Reduce the risk:
Site selection - Avoid valley floors that are frost prone.
Delay pruning - Postpone Budburst until later in the season when risk of frost has lessened.
Grape Variety - Choose late budding varieties.
Canopy Management - Train vines high off the ground.
Avoid cover crops - Bare soil between vines absorbs more heat during the day and radiates it at night.

Damage mitigation:
Aspersion - Irrigation sprinklers or special water sprinklers installed. Must be kept on till temperature rises. (Equipment + water costs)
Wind Machine - 4-7m high fan to pull warm air from the inversion zone to ground level.
Heaters (Oil/Propane - Smudge Pots, Candles - Bougies) - lit when there is a risk of frost. (High cost, fuel, labour, low efficiency and air pollution).