Northern California field trials that feature almond scion grafted to a relatively new Russian hybrid rootstock look promising after eight years, with many positive attributes showing up.
Word has gotten out, and nurseries say they’re seeing strong demand for Krymsk 86, a hybrid between a peach (Prunus persica) and a plum (Prunus cerasifera).
Despite the positive showing, John Edstrom, a University of California Cooperative Extension farm adviser based in Colusa County, says Krymsk 86 isn’t the silver bullet of rootstocks for stone fruit and almonds in the West.
It doesn’t have tolerance to rootknot nematode, and tolerance to oak root fungus and boron are big question marks, he says.
North Central project trials
Researchers who are part of the NC-140 project continue to look at Krymsk 86 as one of 18 rootstocks for peaches in trials at 14 locations in 12 states.
The plots were planted in 2009, so they are in their second year, says Greg Reighard, a pomology professor at Clemson University who also is heading the peach rootstock portion of the NC-140 project.
In South Carolina, he has a plot in the hilly Piedmont area in the western part of the state and one in the Sandhills to the east. Both plots have Red Haven as the scion variety. In addition, both are orchard replant sites, and neither was fumigated before the new trial was planted.
“If you graft peach on it and you plant on a replant site in the Southeast, you may have problems with survival,” Reighard says of Krymsk 86. “On virgin soil, it possibly may do well.”
The researchers will continue to monitor the rootstocks’ performance during the 10-year life of the trial.
Performance out West
Krymsk 86 was released for testing in 1986 as Kuban 86. It is non-suckering and tolerant to calcareous soils. Trees budded to Krymsk 86 are more cold tolerant than the standard peach seedling.
Edstrom has Krymsk 86 in an 8-year-old and a 5-year-old trial with almond as the scion at the Nickels Field Station near Arbuckle, Calif.
“It’s almost the same vigor as peach rootstocks Lovell and Nemaguard,” he says. “It has some amazing attributes. It’s a plum rootstock but it doesn’t sucker like Marianna [2624]. The trees are much better anchored. It could replace some of our peach rootstocks.”
Krymsk 86 also appears to do better in wet soils than peach rootstocks, but Edstrom says a few more years will be needed to see if the observation proves true.
UC nematologist Mike McHenry has evaluated 40 rootstocks as potential replacements for Nemaguard. Part of the work included developing nematode profiles for each rootstock.
Krymsk 86 appears to be susceptible to root-lesion and ring nematode and very susceptible to rootknot nematode, according to trial results.
Nurseries see strong demand
John Arellano, a field rep with Duarte Nursery in Hughson, Calif., says he sees growers’ interest increasing as they learn more about the newcomer.
The rootstock already has been moved into the nursery’s Clean Plant Program, which uses micro-propagation and greenhouse production to ensure a disease-free container-grown tree.
Duarte plans to begin selling trees budded to Krymsk 86 by year’s end.
“So far, it seems to be hitting the numbers,” Arellano says.
He anticipates it being grafted to nonpareil, Monterey and Fritz, since those almond scion varieties seem to be what most growers are ordering on other rootstocks.
“A lot of it will depend on the grower’s choice,” he says.
Like with most other new varieties, Edstrom recommends planting only a few rows to see how Krymsk 86 will perform under your conditions before moving wholesale into the new rootstock.
Contact Vicky Boyd at vlboyd@att.net or (209) 571-0414.
