Disease resistance of ‘MP-29’, a clonal interspecific hybrid rootstock for peach, in post-release trials

Authors: Beckman, Thomas; ROLLINS, ANDY - Clemson University; PITTS, JIM - Auburn University; CHAVEZ, DARIO - University Of Georgia; CHAPARRO, JOSE - University Of Florida

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2018
Publication Date: 4/1/2019
Citation: Beckman, T.G., Rollins, A., Pitts, J., Chavez, D., Chaparro, J.X. 2019. Disease resistance of ‘MP-29’, a clonal interspecific hybrid rootstock for peach, in post-release trials. HortScience. 54(4):638-641. https://doi.org/10.21273/HORTSCI13592-18.
DOI: https://doi.org/10.21273/HORTSCI13592-18

Interpretive Summary: MP-29, a clonal hybrid rootstock for peach, was released for grower trial in 2011. At that time Guardian peach rootstock was the most popular rootstock for the southeastern peach industry, primarily because of its superior resistance to peach tree short life which at the time of Guardian’s release had been the most important cause of peach tree mortality in the Southeast. MP-29 offered resistance to peach tree short life equal to Guardian but then added significant resistance to Armillaria root rot, to which Guardian is highly susceptible and for which there is no chemical management program. Additionally, MP-29 provided broader resistance to root-knot nematodes that did Guardian. Trees on MP-29 are semi-dwarf, typically only 70% the size of trees on Guardian. This reduced vigor offers advantages in tree management by reducing pruning and thinning costs. Productivity and fruit size of trees on MP-29 is equal to if not better than that of trees on Guardian. Following its release, testing of the disease resistance of MP-29 has continued in grower and researcher trials throughout the southeastern production area. This has afforded a more challenging testing regime of MP-29’s qualities under different management programs, on planting sites with different soil types and disease pressure. Through all of these tests MP-29 has continued to display disease resistance superior to that of Guardian.

Technical Abstract: The primary focus of the stone fruit rootstock program at Byron, Georgia has been the development of disease resistant rootstocks for peach (Prunus persica L. Batsch). Historically peach tree short life (PTSL), aka ‘Bacterial Canker Complex’, and Armillaria root rot (ARR) have been the two most important causes of premature mortality of commercial peach trees in the southeastern United States. Guardian, a seedling peach rootstock, was cooperatively released in 1993 by the USDA-Agricultural Research Service and Clemson University. It has since been widely adopted by the southeastern peach industry. As a result, trees losses to PTSL have declined sharply. However, Guardian, like most other peach seedling rootstocks, is very susceptible to ARR. ARR has now moved to the forefront as the primary cause of premature peach tree death in the Southeast. In response to this threat, the Byron program in cooperation with the University of Florida, released ‘Sharpe’, a plum hybrid rootstock in 2007. Despite its broad disease resistance, ‘Sharpe’ proved unsuited for widespread commercial utilization due to its relatively poor cropping performance. In 2011, ‘MP-29’, a semi-dwarf, clonal, plum x peach hybrid, was released for commercial testing. ‘MP-29’s broad disease and nematode resistance in combination with its dwarfing ability and excellent productivity offered great promise for use in this production area and others suffering from similar issues. Since its release, testing of ‘MP-29’ has continued both in researcher and grower trials. To date, performance has exceeded all expectations.