Impact of Meloidogyne incognita on the Incidence of Peach Tree Short Life in the Presence of Criconemella xenoplax.

The relationship between Cricenemella xenoplax alone and in combination with Meloidogyne incognitaon 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 Lovell peach. Tree trunk diameter was significantly reduced in the presence of both nematode species prior to 1993. Soil pH was lowest in the co-infection treatment as compared with the uninoculated control on three of the four sampling dates. In 1994, 80% of the trees growing in soil infested with C. xenoplax alone developed typical disease symptoms and died. The remaining tree died in 1995. No trees died in the M. incognita alone, C. xenoplax + M. incognita, or uninoculated control treatments. Parasitism by C. xenoplax, but not by M. incognita, made Lovell peach trees more susceptible to the disease. These findings were confirmed in an orchard site naturally infested with both C. xenoplax and M. incognita where Redhaven trees budded to Lovell rootstock exhibited a reduction of 1.6 years in average tree life for every centimeter increase in trunk diameter.