The Clonal Advantage at Brokaw




Varieties

 

Clonal Rootstocks

 

Rootstock Tolerances/Advantages Susceptibilities/Disadvantages
Dusa
(Merensky 2)**		 Root rot tolerance, 1 *
Production, 1 *		 Wet feet
Toro Canyon Root rot, 2
Production, 2
Citricola crown rot, 1
Salinity, 1		 Wet feet
Duke 7 Root rot, 3
Production, 1
Citricola crown rot, 2
Tree color
Salinity, 2		 Wet feet
Borchard Production, 1
Lime-induced chlorosis		 Wet feet
Root rot susceptible

CAS New Rootstocks

   Available Commercial Rootstocks
   Dusa®
   Toro Canyon
   Duke 7
   Zerala® (Merensky 5)
   Leola® (Merensky 6)
   Tami (VCBO1)
   Miriam (VC218)
   Ben Ya’ Acov 1 (VC66)
   VC207
   Borchard
   Topara
   Uzi
   Steddom
   Zentmyer

Dusa®

Dusa® (Merensky 2) is a South African selection made by Westfalia Fruit from a tree that was thriving under very wet conditions near a stream. Dusa® is believed to be of Guatemalan x Mexican origin characterized by strong tolerance to Phytophthora cinnamomi and by producing healthy vigorous trees and high yields. Dusa® possesses moderate tolerance to saline conditions and struggles when planted in low, cold areas with poorly drained soils.  

Introduced in the early 2000’s, Dusa has become the dominant clonal avocado rootstock worldwide as of 2023, demonstrating good performance under a wide range of growing conditions. Dusa is the most widely planted selection in California as well as many other avocado producing regions.

Zerala ® (Merensky 5)

This rootstock has demonstrated a noticeable advantage when planted in saline soils. Selected in South Africa for its resistance to Phytophthora root rot, Zerala® supports large canopy volumes and competitive yields. It has been observed to struggle in waterlogged conditions and therefore prefers well-drained soils or berms.

In trials performed by the University of California in Riverside, CA., Zerala® was found to offer an advantage under saline conditions.

Miriam (VC218)

Miriam is another rootstock selection with West Indian genetics that came from the Israeli program. It has recently been released commercially in California. Research shows that it has high tolerance to both Phytophthora cinnamomi and salinity. In California we have only a few years of experience with this rootstock, but Brokaw Nursery is monitoring it’s performance in different growing area.

Note: Miriam is Property of the Agricultural Research Organization of the State of Israel. It is protected by the US Patent US PP30,353

Zentmyer

Zentmyer gets its name from leading avocado pathologist, Dr. George A. Zentmyer from UC Riverside. This vigorous rootstock exhibits strong tolerance to Phytophthora root rot but it is highly susceptible to salinity. Zentmyer performs well with both Hass and Gem as scions as long as salts are not present. 

Note: Zentmyer is property of the University of California and it is protected by the US Patent US PP24,258

Toro Canyon

Another industry standard in California, Toro Canyon was cloned from a survivor tree in a Phytophthora root rot-infested area. Like Dusa, it is thought to have some Mexican race in its genetic makeup. Toro Canyon has moderate tolerance to root rot caused by Phytophthora cinnamomi.  Widely appreciated as a strong and well-behaved rootstock, Toro Canyon tolerates diverse conditions with good grace. It was selected in 1984 and, though it is very difficult to propagate, it continues to be one of our two top selling rootstocks.

Leola® (Merensky 6)

Leola® is one of the selections made by Westfalia Fruit from their Phytophthora screening program. It is one of the latest releases in California and it is showing great promise in the Ventura area.

When grafted with both Hass and GEM, Leola® offers highly competitive yields and supports excellent tree health making it a good candidate for new planting sites. This rootstock also demonstrates strong tolerance to P. cinnamomi when planted in infested soils. For more information on Leola®, click here. 

Note: Leola® is protected as Merensky 6 by the US Patent PP32,465

Ben Ya’Acov 1 (VC66)

Named after one of the pioneers of the Israeli avocado industry, Ben Ya’Acov 1 is a West Indian rootstock that has shown some promise. Research shows that when grafted with Hass, Ben Ya’Acov 1 supports high yields and healthy trees, tolerance to root rot caused by P. cinnamomi and to salinity. 

In California we only have a few years of experience with this rootstock, but Brokaw Nursery is monitoring it’s performance in different growing regions.

Note: Ben Ya’Acov 1  is Property of the Agricultural Research Organization of the State of Israel. It is protected by the US Patent US PP30,447

Borchard

This Mexican rootstock is described as one of the most susceptible to P. cinnamomi but is resistant to P. citricola. In alkaline soils, Borchard can thrive where avocados on other rootstocks show intense chlorosis. When grafted to Hass, Borchard supports high yields and strong growth when Phytophthora root rot and salinity are not present. For more information on Borchard, click here.

Steddom

Steddom is a clonal rootstock selected from a Toro Canyon seedling. It exhibits high tolerance to Phytophthora root rot and behaves well under saline conditions. Once grafted with Hass, the trees are relatively slow growing but produce good yields. Steddom has been planted in some groves in Southern California with good results. 

Note: Steddom is property of the University of California and it is protected by the US Patent US PP24,279

Duke-7

Duke-7 was the first clonal rootstock selection released in the 1970’s and it is still a rootstock of commercial interest around the world. 

This rootstock behaves well under cold conditions and is less susceptible to chlorosis during winter compared to other rootstock selections. Its tolerance to P. cinnamomi is moderate. Duke-7 does not do well under waterlogging conditions and does not perform well under saline conditions.

Tami (VC801)

Tami is a selection from the program developed by A. Ben-Ya’cov in Israel that identified high yielding rootstocks growing under saline conditions. 

Tami was imported into California in the early 2000’s. It has demonstrated strong tolerance to saline conditions in Israel. Early observations indicate that when grafted with Hass and planted in southern California, Tami produces competitive yields and healthy trees. 

Note: Tami is Property of the Agricultural Research Organization of the State of Israel. It is protected by the US Patent PP30,384.

Day (VC207)

A selection made in Florida, US. The Day is said to perform well under saline conditions and in the presence of Phytophthora cinnamomi.

Topara™

This selection originated from a vigorous productive tree growing in the Topara region of Perú. Topara™ rootstock induces high vigor when grafted to Hass. If Phytophthora root rot is under control, it can induce good yields in Hass. Due to its origins in the sandy Peruvian coast, it is thought it would have good behavior under saline conditions, but more research is needed.

Note: Topara™ is protected in the USA as KB1 under the US Patent US PP29,767

Uzi

Named after Uzi Afek, a scientist from the Volcani Center in Israel, this clonal rootstock is extremely vigorous and fast-growing with high tolerance to Phytophthora root rot. When grafted with Hass, it can induce a vigorous tree and high yields if salinity is not present. 

Note: Uzi is property of the University of California and it is protected by the US Patent US PP 24,278

Notes from the Field 9/16/24

Leaf analysis is a useful tool for developing a strategy for fertilizing an avocado orchard.  Ideally, a relationship between the […]