From the cherry breeding conducted by Amy Iezzoni, professor emeritus at Michigan State University, five new dwarfing and early rootstocks have recently been commercially released: the Corette® series. All five rootstocks significantly reduce the size of the tree compared to standard rootstocks and entry into production occurs within the third year, two years earlier than traditional planting systems. These rootstocks have completed the experimentation phase in the USA both for sweet cherry, in very high density wall planting systems, and for sour cherries, using a high density production system and mechanized harvesting above the row.
The main characteristics of the Corette® series rootstocks are reported below (Iezzoni, 2022).
Dwarfing, precocity-inducing, clonal rootstock for cherry.
Origin: Michigan State University, East Lansing, by A. Iezzoni. Hybrid of unknown complexity involving Prunus avium, P. cerasus, and P. fruticosa. USPP 30,553; 4 June 2019.
Plant: vigor weak; branching habit spreading.
Rootstock performance: induces reduced vigor and increased precocity compared to trees budded on mazzard seedling rootstocks; vigor lower than Gisela® 5; grafted plants tend to produce root suckers; exhibits moderate sensitivity to high soil pH.
Dwarfing, precocity-inducing, clonal rootstock for cherry.
Origin: Michigan State University, East Lansing, by A. Iezzoni. Hybrid of unknown complexity involving P. avium, P. cerasus, and P. fruticosa. USPP 32,852; 2 Mar. 2021.
Plant: vigor weak; branching habit spreading.
Rootstock performance: induces reduced vigor and increased precocity compared to trees budded on mazzard seedling rootstocks; vigor lower than Gisela® 5; grafted plants tend to produce root suckers.
Dwarfing, precocity-inducing, clonal rootstock for cherry.
Origin: Michigan State University, East Lansing, by A. Iezzoni. (P. cerasus × P. canescens) O.P. USPP 30,538; 28 May 2019.
Plant: vigor weak; branching habit spreading.
Rootstock performance: induces reduced vigor and increased precocity compared to trees budded on mazzard seedling rootstocks; vigor similar to Gisela® 5; grafted plants produce no root suckers.
Dwarfing, precocity-inducing, clonal rootstock for cherry.
Origin: Michigan State University, East Lansing, by A. Iezzoni. P. cerasus × (P. cerasus × P. canescens). USPP 30,473; 7 May 2019.
Plant: vigor weak; branching habit spreading.
Rootstock performance: induces reduced vigor and increased precocity compared to trees budded on mazzard seedling rootstocks; vigor similar to Gisela® 5; grafted plants produce no root suckers.
Clonal rootstock for cherry.
Origin: Michigan State University, East Lansing, by A. Iezzoni. Hybrid of unknown complexity including P. avium and P. fruticosa. USPP 32,813; 16 Feb. 2021.
Plant: vigor weak; branching habit spreading.
Rootstock performance: induces reduced vigor and increased precocity compared to trees budded on mazzard seedling rootstocks; vigor lower than Gisela® 5; grafted plants tend to produce root suckers; exhibits tolerance to water stress compared to Gisela® 5.
L. Long, G. Lang, C. Kaiser (2020). Sweet Cherry. CABI Books
A. Iezzoni (2022). Cherry Rootstocks. Register of New Fruit and Nut Cultivars List 51. HORTSCIENCE
15 May 2024
A survey conducted at the beginning of May among the main industry players predicts a below-average production in 2024 of between 50 and 60 thousand tonnes around +/- 10% compared to last year's production, with negative estimates prevailing.
20 Nov 2024
Some dwarfing rootstock selections for Gisela® cherry trees have recently been licensed in New Zealand and will be more widely available to growers from 2026. Gisela® 12 and 6 are currently being tested in Central Otago.
28 Oct 2026
No single test currently provides a universally conclusive diagnosis. Nevertheless, combining anatomical observations, physiological and biochemical indicators, and molecular and digital tools can shorten assessment times and reduce grafting failures.
28 Oct 2026
Overall, the season sees some traditional leaders lose volume, including San Francisco, Copefrut and Verfrut, while Dole gains ground and some new exporters make a strong entry into the top 20.
