2.2 Budburst Flashcards
What is another word for budburst?
Budbreak
What is budburst?
- When buds swell and open, and green shoots start to emerge
What are the four factors that determine when budburst occurs?
- Air Temperature
- Soil Temperature
- Grape Variety
- Human Factors (e.g. late winter pruning)
What temperatures are needed for a compound bud to burst?
Average air and soil temps >10 deg C
Why can regions that have marked differences in temperature between the various seasons (e.g continental climates) be advantageous for successful budburst?
Rapidly increasing temperatures in the spring mean that budburst can be relatively uniform and this has positive implications for the homogeneity of later stages in the growing season, potentially eventually leading to a crop of grapes with even ripeness
Why can regions that have less contrast between winter and spring temperatures (for example, maritime climates) be disadvantageous for budburst?
- Budburst can be less synchronised and uneven
- Problems can occur when a few unusually mild winter days cause early budburst; any cold days and frosts that follow can potentially harm the newly burst buds, leading to lower yields.
What types of soil temperatures encourage earlier budburst?
- Higher soil temperatures around the roots encourage earlier budburst
What types of soils are beneficial in cooler climates? Why?
- Dry, free-draining soils (e.g sandy soils)
- Tend to warm up more quickly than water-storing soils (e.g. clay-rich soil)
- Can be advantageous in cool climates where an early start to the growing season improves the chance of ripening
What is an early budding grape variety? Name 4 early budding grape varieties.
Grape varieties that require relatively low temperatures at budburst
- Chardonnay
- Pinot Noir
- Merlot
- Grenache
What is a late budding grape variety? Name 3 late budding grape varieties.
Grape varieties that require higher temperatures are referred to as ‘late budding’
- Sauvignon Blanc
- Cabernet Sauvignon
- Syrah
Which are at a greater risk for spring frost: early budding or late budding varieties?
Early budding
Is budding time linked to ripening time?
No. Time of budding is not always linked to time of ripening and hence a grape variety that is early budding is not necessarily also early ripening. For example, Grenache buds early and ripens late.
What human factor can advance or delay budburst? Why might this be carried out?
- Carrying out winter pruning late in the dormant period can postpone budburst
- This technique can be used in areas where spring frost is a known problem.
When is Budburst in the Northern Hemisphere?
March–April
When is Budburst in the Southern Hemisphere?
September–October
