Rootstocks

Question 1

Rootstocks, general

Answer 1

Most rootstocks combo of Vitis berlandieri, riparia, rupestris

Riparia: low vigor, shallow-rooting, early ripening, damp tolerant, susceptible to chlorosis

Rupestris: high vigor, deep-rooting, late ripening, drought-tolerant, susceptible to chlorosis

Berlandieri: high vigor, deep-rooting, HIGH RESISTANCE TO CHLOROSIS. Cuttings have a hard time rooting, so rarely used as pure species, inefficient at potassium uptake THEREFORE less cation exchange THEREFORE acidity retained

Question 2

Past exam questions

Answer 2

2011: What are the vineyard factors that influence the choice of rootstock?
2002: Discuss the factors that influence the choice of rootstock and scion.

Question 3

Rootstock selection

Answer 3

Based on:

• Calcium content of soil (measured as pH, as a %, or as the IPC – the Index of Potential Chlorosis, which considers both size of chalk particles and total iron content)
• vigor of vine / fertility of site
• depth of soil
• water-holding capacity of soil
• acidity of soil (excess acid can lead to aluminum toxicity in rootstocks)
• cultivar (scions with problems at flowering or with wood ripening should not be grafted onto vigorous rootstock)
• climate (use low vigor stocks in cool climate to shorten vegetative cycles)
• yield/quality (low vigor stocks for fine wine)

note: the world is moving toward rupestris because of drought. The trouble there is that it’s late ripening. Will we move to earlier ripening clones to compensate?

Question 4

Examples

Answer 4

UK: all rootstocks are berlandieri x riparia. surface rooting, damp tolerant, chalk tolerant.
- AKA 5BB, 125AA, 5C, SO4 (420A also berlandieri x riparia, but not in UK)

berlandieri x rupestris: 99R, 110R, 140R, 1103P

riparia x rupestris: 3309, 101-14, Schwarzmann

Good drought tolerance: St George, 99R, 110R, 140R, 5BB, 1103P

Good for acid soils: 99R, 110R, 140R

Good for alkaline soils: 41B, 420A, 5BB

NAPA:

• Mike Hirby of Relic ringing new vineyard with Riparia Gloire
• Snowden, RE Diana Seyss, all AxR, then all 420A (low vigor), she wishes she had lobbied for St George for its drought-tolerance and longevity (but it is low yielding).
• Kelly Maher, many sites in Napa are volcanic, which are high in Potassium. 101-14 absorbs K+, which drives up pH; by extension, 110R is good volcanic rootstock because it is a poor assimilator of K+
• Harlan also uses 110R, good for drought resistance and dry-farming

BURGUNDY:
- Diana Seyss, at Dujac, all selected for limestone tolerance. 161-49, riparia gloire, 3309, 34EMzz

Question 5

Nematodes

Answer 5

Dr. Andy Walker at UC Davis developed GRN series… is less vigorous than 039-16 and no vinifera