It comes from a Mexican seedling that was selected in the 50's by Dr. G. Zentmyer, but it was not marketed until mid-70s. It was the first variety of rootstock available against root rot caused by Phytophthora cinnamomi
and is still recommended as rootstock in California and South Africa for its productivity.
This rootstock is vigorous, with good frost tolerance. Its tolerance to is moderate but is more tolerant to Phytophthora citricola instead. Produce good fruit size early in the season. Tend to stay green in cool soils during winter when trees are more susceptible to chlorosis. Moreover, it induces a less alternate bearing than other rootstocks. It is not recommended for poor aerated soil, salinity problems or replanting.
Dusa (Merensky 2)
It's a Mexican rootstock. Hass avocado grafted on Dusa is more productive than on Duke 7. It has a high tolerance to salinity and root rot caused by Phytophthora cinnamomi. It is a new rootstock that is not yet widespread in Spain, however, is the most commonly used in California. This rootstock is suitable for replanting.