Breeding Peaches for Root-knot Nematode Resistance1

Abstract

Abstract Five peach rootstock selections show immunity to root-knot nematode disease caused by Meloidogyne incognita (Kofoid and White) Chitwood and M. javanica (Treub) Chitwood. These are the first peach rootstocks which remain free from galls when exposed to both these root-knot nematode species. They are derived from a 1949 cross in Chico, California, of Prunus davidiana Franch with a Chinese Peach. Resistance to the species M. incognita and M. javanica depends on different genes. Resistance to the former was inherited as a monofactorial dominant. Resistance to M. javanica appeared dependent on 2 or more dominant genes in both ‘Okinawa’ and P. davidiana , but P. davidiana progenies were completely free from visible galls. A third type of root-knot nematode was discovered in Florida in 1966. It reproduces readily on ‘Okinawa’, ‘Nemaguard’ and the other lines which have been selected for resistance or immunity to M. incognita and M. javanica .