"VVA-1 is a Russian rootstock that in a Dutch test with Opal clearly showed weaker growth compared to St Julien A, with a higher production capacity and fruits of similar size. The leaf condition and graft union look normal, and there are no root suckers. This rootstock may therefore prove to be a real asset. Well-founded advice will, however, require more empirical data."
19th Variety list of large-fruit plants 1999.
"Table 1 shows some preliminary data of a Dutch trial with Opal plum, that look very encouraging, with dwarfed growth and increased cropping efficiency. After five growing seasons, the union between scion and rootstock is still without any bulbing."
Rootstock Guide Apple, Pear, Cherry, European Plum 1998