Hazards Pests And Diseases Flashcards
Drought
Min needs 500mm/year in cool climate and 750mm/year in warm
Stomata close and reduce photosynthesis
Drought management
Irrigation where allowed
Drought resistant rootstock from Rupestris and Berlandieri parentage
Drought tolerant varieties like Garnacha
Excessive water
In summer = vegetative growth (divert nutrients from bunches and shade bunches)
Fungus
Waterlogged soil reduces oxygen availability and compacts soil
Excessive rainfall mgmt
Slope, free draining soil, or drainage system
Untimely rainfall
During pollination and fruit set can lead to millerandage or coulure reducing size of crop and lowering quality
Rainfall around harvest swells grapes to splitting and can lead to grey rot, makes harvest work difficult
Freeze
-4*F can damage or kill vine
Freeze mitigation
Site selection- hillside is warmer, near body of water, allow depth of snow to insulate
Variety choice- cab franc/riesling, hybrid or American varieties
Protect vines- hilling up for insulation, burying the vine, pruned to have several trunks
Frost
Advective frost- large volumes of cold air moving in from cold areas
Radiative frost- heat lost on still, cold nights
Frost risk reduction
Site selection to avoid frost pockets
Delayed pruning postpones budburst
Late budding varieties like Riesling
High trained vines
Bare soil between vines absorb more heat and radiate it
Frost mitigation
Sprinklers - aspersion - only method to combat advective frost
Wind machine- pull warm air down can use helicopter
Oil or propane heater (smudge pot) or wax candle (bougies)- low heating efficiency
Hail
Damage to vines at all stages of development
Hail mgmt
Silver iodide seeding- causes rain rather than hail
Netting- only good in high sunlight areas
Plots in varied areas
Crop insurance
Sunburn
Scars skin possible death of grape
Bitter taste
Increased susceptibility to rot
Sunburn mgmt
Row orientation and aspect reduce impact of hottest afternoon sun
Canopy mgmt techniques to adjust direct exposure
Irrigation to lower water stress
Agricultural sunscreen or cloth/net
Fire
Damage to property, equipment, irrigation system, vines, trellises
Smoke taint
Fire mgmt
Fire detection and sprinklers
Water tank install
Employee training
Smoke taint
Effect on fruit increases from veraison onward
Aroma compounds in smoke absorbed in grapes and bind with sugars to form precursors that become aromatic through fermentation
Strength of aroma increases during aging
Smoke taint mgmt
Musts tested analytically or by micro fermentation to establish extent of problem
Thought to be in skin so reducing skin contact reduces taint - hand harvest/gentle or whole bunch press/ low temp fermentation/ reduced maceration
Flash detente- can help but not remove completely
Can blend into unaffected wines to dilute
Phylloxera
Vines die of drought in larger and larger patches
Vine roots covered with insects and yellow eggs
Swelling on older roots
Pale green galls underside of leaves
Slow, stunted growth and leaf yellowing in three years after exposure, death in 5
Phylloxera mgmt
Grafting however American rootstock has poor like tolerance
Rootstock hybrids add lime tolerance
Now rootstocks offer protection from various pests/hazards