SATI Beyond The Bunch 2nd Quarter 2026

Based on overall performance, Ramsey is a good option for rapid vineyard establishment. It has strong vegetative growth and adapts well to a range of environments. SO 4 also merits consideration, given its high, stable yields and consistent reproductive performance.

When considering performance across all sites, the top yielding rootstocks were Paulsen 1103, Ramsey, Richter 110, and SO 4. Of these, Ramsey and SO 4 had the heaviest bunches and largest berries.

Table 1. General and growth traits of rootstocks in Phase 1. Ramsey is the control. Rootstock Yields 1 Vigour 2 Bud-break earliness 3

Scion:rootstock diameter 4

Harmony

Medium to low overall. Performed better at Vorentoe than other sites. High to medium overall. Similar to Ramsey except for low yields at Vorentoe.

Similar to Ramsey at all sites except Begin where it was less vigorous. Variable. Similar to Ramsey at Yarona. Lower at Begin and Buffelskraal. Low at Vorentoe.

Medium to late overall and at all sites

Optimal: Vorentoe. Yarona. Not optimal: Begin. Buffelskraal. Denau. Optimal: Begin. Buffelskraal. Yarona. Not optimal: Denau. Vorentoe. Optimal: Buffelskraal. Denau. Yarona. Not optimal: Begin. Vorentoe. Optimal: Begin. Buffelskraal. Denau. Vorentoe. Not optimal: Yarona. Optimal: Buffelskraal. Vorentoe. Yarona. Not optimal: Begin. Denau.

Paulsen 1103

Late overall. Medium to late at individual sites.

Ramsey

High overall and at all sites.

High at all sites.

Early to medium overall and at all sites.

Richter 110

High to medium overall. Variable performance at individual sites.

Low at all sites except Yarona where it was similar to Ramsey.

Late overall. Medium to late at individual sites.

RS-3

Similar to Ramsey overall and at all sites.

Medium to low at all sites except Buffelskraal where it was similar to Ramsey. Medium to low at all sites except Buffelskraal where it was similar to Ramsey.

Early overall. Early to medium at individual sites.

RS-9

Low overall and at individual sites.

Early to medium overall. Early at Begin and Denau and medium at Yarona. Medium to late overall but variable at individual sites. Early at Yarona but late at Begin and Denau.

Optimal: Begin. Buffelskraal. Vorentoe. Yarona. Not optimal: Denau.

Ruggeri 140

Low overall and at individual sites.

Similar to Ramsey at all sites.

Optimal: all sites.

SO 4

High overall and at all sites.

Variable. Similar to Ramsey at Vorentoe. Lower at Begin and Buffelskraal. Low at Yarona.

Medium overall. Medium to late at Denau and late at Begin and Yarona.

Optimal: Buffelskraal. Denau. Not optimal: Begin. Vorentoe. Yarona.

1 Yields differed between rootstocks for all sites combined as well as at Begin, Vorentoe, and Yarona individually. 2 Vigour is based on cane mass. Vigour differed between rootstocks at Begin, Denau, Vorentoe, and Yarona individually. 3 Earliness differed between rootstocks for all sites combined as well as at Begin, Denau, and Yarona individually. 4 Ideal scion:rootstock diameter is 0.9–1.1. Ratios outside this range indicate less optimal scion:rootstock compatibility. It differed between rootstocks at all sites individually.

BEYOND THE BUNCH • 9 • QUARTER 2 • 2026