Temperature and Age of Plant Affect Resistance in Peach-Almond Hybrid Rootstock Infected with Meloidogyne javanica

Abstract

The influence of temperature and age of the plant was determined on nematode reproduction on a susceptible almond (Prunus amygdalus Batsch.) and on a resistant peach-almond hybrid (P. persica Stok. × P. amygdalus Batsch.) rootstock inoculated with Meloidogyne javanica (Treub) Chitwood. Experiments were conducted under greenhouse conditions in heated and unheated sand beds. `Garrigues' almond inoculated with 3000 nematodes per plant showed extensive galling, high final nematode population levels, and high counts of nematodes per gram of root at 27 and 32C. The hybrid G × N No. 1 showed minimal galling and reproduction at 27C but higher levels of galling and final population and nematode counts per gram of root at 32C, suggesting a partial loss of resistance with temperature increase. One-month-old and 1-year-old plants of `Garrigues' were susceptible following inoculation with 2000 nematodes per plant, although plantlets (l-month) were significantly more affected. Plantlets of hybrid G × N No. 1 were also susceptible, but 1-year-old plants were resistant. Resistant genotypes (G × N selections) seem to require root tissue maturation before expressing full resistance.