Performance of Geneva® Apple Rootstock Selections with 'Brookfield Gala' and 'Cripps Pink' in a Tall Spindle System

Abstract

High density orchard systems have become standard in many apple production regions due to their earlier yield and higher cumulative yields, which results in greater return on investments. Growers in the Mid-Atlantic region have unique challenges compared to northern production regions—warm temperatures, long growing seasons, and high incidence of fire blight—which elevates the financial risk to growers that invest in the extremely high establishment cost of these systems. High density orchard systems have not been widely evaluated in replicated trials under these growing conditions, so it is unknown whether they are suitable for the region. In addition, there is little information on the performance of a suite of new rootstocks released from the Geneva breeding program designed for these high density systems in the Mid-Atlantic region. To test these high density systems and the relevant rootstocks, two scion cultivars (‘Brookfield Gala’ and ‘Cripps Pink’) were budded on stoolbed propagated G. 41, G. 202, and G. 935 as well as tissue-culture propagated G. 202.

Results support that the tall spindle system is appropriate for orchards in the Mid-Atlantic, but could be optimized with region-specific recommendations. The rootstocks tested were appropriate for tall spindle orchards in the Mid-Atlantic; however, there was a high incidence of tree death due to graft union breaks, particularly with ‘Cripps Pink’ on G. 41, and certain scion-rootstock combinations were too vigorous. Additionally, high amount of fire blight not controlled with standard practices indicate that care must be taken in determining a pruning and training regime for this planting system in the Mid-Atlantic. ‘Cripps Pink’ fruit quality was not affected by rootstock, while ‘Brookfield Gala’ quality was affected by choice of rootstock. Yield efficiencies for both cultivars were lower than expected. Propagation method did not appear to significantly impact production, but did have an effect on tree size.