Rootstocks were a big part of the International Fruit Tree Association’s annual conference general session kickoff. And it’s no surprise since rootstocks play such a key role in all that tree fruit growers do.
In fact, Gennaro Fazio of USDA-ARS says he and his research team are learning just how much influence a rootstock can have on the scion. He says they are noticing the rootstock can change the scion at a molecular level, imparting some genetic traits to the scion, like fire blight resistance.
Fazio, of Geneva rootstock fame, says he is looking at genetic markers to help predict size, how PGRs will interact with the tree, and how fruit quality may be influenced by rootstock.
He also says chilling requirements are also influenced by rootstocks.
Fazio hopes through more studies to crack the calcium deficiency issues that Honeycrisp has.
Rootstocks also were a topic in sweet cherries were Lynn Long of Oregon State University reviewed his studies on the rootstocks currently available as well as some on the horizon.
Out West growers prefer the Krymsk series, which Long says is for many reasons, there are lower royalty costs, they perform well in hot climates, are moderately productive, and perform better than Mazzard.
Long says there is potential for the soon-to-be-released Weigi cherry rootstocks as well as two new Gisela rootstocks – Gi.13 and Gi.17. Studies continue to be conducted on the new Michigan State University rootstocks. He says the MSU rootstocks may be a game changer because some advance ripening, allowing growers to get in the market sooner.
Todd Einhorn of Oregon State University gave a look at current pear rootstock research and says OHxF 87 has performed the best, when compared with rootstock internationally available. The trouble with many rootstocks available internationally for pears, are most are not cold hardy.
Einhorn says cold hardiness is a focus of some upcoming studies on pear rootstock.
Greg Reighard of Clemson University focused on research in peach rootstocks.
The biggest challenge with peaches, he says is to “keep ’em alive.”
Reighard’s studies are to find rootstocks to modify the canopy for mechanization, tolerate soil conditions, and increase yield efficiencies.
He says some semi-dwarf and dwarfing peach rootstocks have survival issues. Also, some plum hybrids advance maturity.
But, he says MP.29 is one that is upcoming, as rootstock research continues in peaches.