IMPACT OF MELOIDOGYNE-INCOGNITA ON THE INCIDENCE OF PEACH-TREE SHORT LIFE IN THE PRESENCE OF CRICONEMELLA-XENOPLAX

The relationship between Criconemella xenoplax alone and in combinatio n with Meloidogyne incognita on the incidence of peach tree short life disease was studied in field microplots during 1989-96. The presence of M. incognita suppressed the population density of C. xenoplax on Lo vell peach. Tree trunk diameter was significantly reduced in the prese nce of both nematode species prior to 1993. Soil pH was lowest in the co-infection treatment as compared with the uninoculated control on th ree of the four sampling dates. In 1994, 80% of the trees growing in s oil infested with C. xenoplax alone developed typical disease symptoms and died. The remaining tree died in 1995. No trees died in the M. in cognita alone, C. xenoplax + M. incognita, or uninoculated control tre atments. Parasitism by C. xenoplax, but not by M. incognita, made Love ll peach trees more susceptible to the disease. These findings were co nfirmed in an orchard site naturally infested with both C. xenoplax an d M. incognita where Redhaven trees budded to Lovell rootstock exhibit ed a reduction of 1.6 years in average tree life for every centimeter increase in trunk diameter.