Field Screening of 25 Advanced Rootstock Selections for Peach (Prunus persica L.) Production in Florida

Peach production in Florida is challenged by the presence of nematodes in the sandy soil characteristic of the growing region. Root-knot nematode species i.e. Meloidogyne incognita, M. javanica, M. floridensis, and M. arenaria are particularly problematic, damaging the root system, and limiting the root development of peach rootstocks. ‘Nemared,’ ‘Nemaguard,’ and ‘Okinawa’ were initially utilized in the southeast to provide resistance to M. incognita, and M. javanica. Following detection of M. floridensis in the region during the 1960’s, ‘Flordaguard’ was released providing improved resistance to the M. floridensis. Due to the exclusive use of ‘Flordaguard’ in Florida, there is the potential for development of nematode strains that overcome its nematode resistance. In addition the high degree of susceptibility to Botryosphaeria gummosis of ‘Flordaguard,’ it was necessary to reinitiate development of improved rootstocks.

A set of advanced rootstock selections with improved horticultural characteristics was developed by the University of Florida Stonefruit Breeding Program. Seeds were collected in the summer of 2014 to create 25 open-pollinated seedling families for field trials. A randomized block design was used to screen the material at Gainesville, FL; and Fort Pierce, FL. Destructive sampling was used to generate preliminary data alternate seedling trees of each selection. Observations were made for nematode susceptibility, tree vigor, and degree of branching. Preliminary observations were made after 9 months of growth during the spring of 2016.

Nematode susceptibility results from Gainesville, FL, where nematode populations are prevalent suggest that a Prunus mume Siebold & Zucc. selection possesses high levels of resistance to root-knot nematodes. Other lines originating from interspecific crosses between ‘Okinawa’ (P. persica L.) x P. kansuensis Rehder. show no significant differences in nematode susceptibility when compared to ‘Flordaguard’ the industry standard at the Gainesville, FL site. Significant differences were detected between families for vigor and branching at the Gainesville, FL site. Trends for reduced branching, and increased vigor were observed in crosses with ‘Flordaguard’ at both locations. Several lines performed better than ‘Flordaguard’ for nematode resistance, vigor, and reduced branching, and will be advanced in the breeding program.