An Induced Resistance Effect of Hydroxyurea on Plants Infected by Meloidogyne javanica.

Aqueous solutions of hydroxyurea (HU) in various concentrations were applied as soil drenches to Meloidogyne javanica-infected plants. At a concentration of 15 ppm, the chemical hampered giant cell formation and the number of females on the roots was 20% of that of the control but the growth of the host plants was not affected. Additional HU applications after the one at infection did not add to the inhibitory effect. HU exerted its effect on M. javanica-infected tomato in five soil types. Soil temperature of 32 C neutralized the HU-induced resistance in much the same way that high temperature breaks the natural resistance in M. incognita-resistant tomato. This study provides further evidence of the role of HU as an induced resistance agent.