2.2 Budburst

Question 1

What is another word for budburst?

Answer 1

Budbreak

Question 2

What is budburst?

Answer 2

• When buds swell and open, and green shoots start to emerge

Question 3

What are the four factors that determine when budburst occurs?

Answer 3

• Air Temperature
• Soil Temperature
• Grape Variety
• Human Factors (e.g. late winter pruning)

Question 4

What temperatures are needed for a compound bud to burst?

Answer 4

For buds to burst, sufficiently high temperatures are needed (average air temperature approximately 10°C / 50°F)

Question 5

Why can regions that have marked differences in temperature between the various seasons (e.g continental climates) be advantageous for successful budburst?

Answer 5

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

Question 6

Why can regions that have less contrast between winter and spring temperatures (for example, maritime climates) be disadvantageous for budburst?

Answer 6

• 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.

Question 7

What types of soil temperatures encourage earlier budburst?

Answer 7

• Higher soil temperatures around the roots encourage earlier budburst

Question 8

What types of soils are beneficial in cooler climates? Why?

Answer 8

• 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

Question 9

What is an early budding grape variety? Name 4 early budding grape varieties.

Answer 9

Grape varieties that require relatively low temperatures at budburst

• Chardonnay
• Pinot Noir
• Merlot
• Grenache

Question 10

What is a late budding grape variety? Name 3 late budding grape varieties.

Answer 10

Grape varieties that require higher temperatures are referred to as ‘late budding’

• Sauvignon Blanc
• Cabernet Sauvignon
• Syrah

Question 11

Which are at a greater risk for spring frost: early budding or late budding varieties?

Answer 11

Early budding

Question 12

Is budding time related to ripening time? Give an example that proves this.

Answer 12

• No.

- Grenache buds early and ripens late.

Question 13

What human factor can advance or delay budburst? Why might this be carried out?

Answer 13

• 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.

Question 14

When is Budburst in the Northern Hemisphere?

Answer 14

March–April

Question 15

When is Budburst in the Southern Hemisphere?

Answer 15

September–October