Flashcards in Hazards, Pests and Diseases Deck (92)
What is amount of rain needed for good quality fruit
For cool climates: 500mm/19.6 in
For warm climates: 750mm/29.5in.
Name all of the hazards vineyards can face?
What happens to the vine when there is a lack of water?
Vines close the stomata to retain water
reduced/stopping of photosynthesis
Growth of the vine shuts down
grape sized is reduced
ripening slows down.
If it is a prolonged drought the vines can lose their leaves and die
Is irrigation legal everywhere?
How can extended drought affect the final wine?
When the plant shuts/slows down due to lack of water, ripening will also slow down.
This can lead to unripe grapes and lower yields.
What are the managements options for drought?
- Irrigation (where allowed by law)
- If it is a new vineyard being planted, drought-resistance root-stock should be high on the list of priorities
Choosing drought tolerant varieties
What are examples of root-stocks that are drought-resistant?
Root-stocks based on V. rupestris and V. berlandieri
110R adn 140R
What are the negative affects of excess water?
Too much vegetative growth that will compete with grape ripening
Excessive shading due to vegetative growth
Higher risk of fungal diseases due to high humidity
If the soils are not free draining, then waterlogging can occur, reducing oxygen available to the roots (which can lead to death)
Waterlogging can also lead to compacted soils, making them harder to work and uncontrolled water run-off.
What are the management options for excess water?
Proper site selection when planting the vineyard to insure that it is planted on a slope or on free-draining soils or the construction of a drainage system
What are the side-effects of untimely rainfall?
-If the rain comes during pollination and fruit set it can lead to millerandage or coulure, reducing crop size and potentially lowering the quality
-Mid-season rain can reduce the rate of ripening
-Heavy rainfall close to harvest can lead to water swelling, reducing the concentration of the must, potentially splitting of the skins leading to grape rot.
-Rains near harvest can also make it harder to harvest if using mechanical harvesters on clay soils
What are the management options for untimely rainfall?
Nothing can be done about the rain, but having a good site (on a slope), soil condition and good drainage can mitigate some of the effects.
Monitoring the forecast and deciding if they would rather harvest with potentially less-ripe grapes vs. losing some, if not all, of their crop.
If temperatures fall below _______, the vine can be seriously damaged or killed by winter freeze
What is the most susceptible part of a grafted vine?
Where the graft is
What are the management options for a potential winter freeze? (There are a lot)
Hillsides can be 5°C/9°F warmer than the valley floor
Vineyards near large or deep bodies of water benefit from a moderating affect
Vines should be planted where the snow settles most thickly, as a deep layer of snow will protect the vines.
Choice of varieties:
Some varieties are most freeze resilient (Riesling and Cab Franc)
Some American and Mongolian vine species are extremely winter hardy, as are they hybrids with these species
Protecting the vines:
Building up the soil around the graft (hilling up) is common in colder regions since the soils underground are only a few degrees below freezing.
Burying the vines is another approach used in extreme climates, but is very costly due to the amount of labor needed.
Vines can be pruned to have several trunks in-case on is killed during the winter.
What is a frost defined as?
A frost occurs when the cold air below freezing collects at ground level.
This will freeze the water in the vine's growing buds and shoots.
When are frost the most damaging to the grape vine?
Right after budburst
Name the two types of frost
Advective Frost: cause by large volumes of cold air moving in from cold areas
Radiative Frost: the result of heat being lost on still, cool nights.
What are some ways that frost risk can be reduced?
Site Selection: making sure you don't pick a frost pocket, or getting a hillside location
Delaying pruning: by doing so, budburst is pushed back into warmer months
Choosing late budding varietals like Riesling
Trainging vines higher off the ground
Having bare soil between the vines so it can absorb more heat during the day
What are the three main options for vineyard owners to use when frost threatens?
Water Sprinklers (also known as aspersion)
Oil or Propane gas heaters
How do water sprinkles help prevent frost from setting?
As the water freezes around the plant, it releases the latent heat, protecting the plant.
* The system must be kept on until the temp rises
How do wind machines help prevent frost from settling?
Wind machines are large fans (13 to 23ft tall) that pull warm air from above down to ground level, thereby raising the temp.
* Helicopters can be used, but generally aren't due to the large expense of owning one
What is an inversion layer?
It is a zone of warm air 10m/33ft above the ground that is usually 5-9°F warmer
What are the drawbacks to using Oil or Propane burners ?
High cost of fuel and labor, low heating efficiency and contributions to air pollution
What is hail?
Frozen pellets of rain
What are some of the management options for hail?
Firing rockets into thunderclouds, seeding them with silver iodide which causes rainfall rather than hail.
Putting nets on to protect the ripening grapes (usually done in regions with high levels of sunlight.
Having numerous plots in different areas
Growers may have to consider the additional cost of crop insurance against hail.
In prolonged hot weather, grapes transpiration is much more limited and as a result, grapes can reach higher temperatures and become burnt.
What are some of the negatives associated with Sunburn?
- Scars on the skin of the grape
- In extreme cases, eventual death on the grape
- Grape quality suffers
- Browning of the grape can give a bitter taste
- Higher susceptibility to rot
What are some of the management options for Sunburn?
- Row orientation and aspect when designing a new vineyard
- Manage the amount of sun exposure with canopy management
- If there is a heatwave in the forecast, additional irrigation (where allowed) may be used
- A special agricultural sunscreen spray can be applied or the vines can be shaded by cloth/net.
What are the management options for fighting fires
- Installing fire detectors and sprinklers
- Installing and maintaining a water tank
- Providing employee training for action in the event of an emergency