Peach Rootstock Development for the Southeastern United States

The primary focus of the stone fruit rootstock program at Byron, Georgia has been the development of disease resistant rootstocks for peach. 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. However, following the cooperative release of Guardian rootstock by the USDA-Agricultural Research Service and Clemson University in 1993 the southeastern peach industry has enjoyed a marked decline in incidence of PTSL. Unfortunately, Guardian, like most other peach seedling rootstocks, is very susceptible to ARR. As a result, ARR has now moved to the forefront as the primary cause of premature peach tree death in the Southeast. Since its inception in 1988, the Byron rootstock program has focused on the breeding and development of new peach, plum and plum x peach interspecific hybrid rootstocks with resistance to PTSL, ARR and several species of root-knot nematode including Meloidogyne incognita, M. javanica and M. floridensis. M. floridensis is a recently identified nematode species with demonstrated ability to attack many of the current commercial peach rootstocks with resistance to M. incognita, including Okinawa, Nemared, Nemaguard and Guardian. Our breeding and evaluation work has recently culminated in the release of two clonal rootstocks with broad disease and nematode resistance. 'Sharpe', a semi-dwarf, clonal, plum hybrid, was released in 2007 for commercial testing and as a germplasm line. 'MP-29', a semi-dwarf, clonal, plum x peach hybrid, was released in 2011 for commercial testing. 'MP-29's broad disease and nematode resistance in combination with its dwarfing ability and excellent productivity offers great promise for use in this production area and others worldwide suffering from similar maladies.