Effect of chemical resistance inducers on the control of <I>Monosporascus</I> root rot and vine decline of melon

Abstract

The effect of the resistance inducers methyl jasmonate (MeJA), acybenzolar-S-methyl (BTH) anddipotassium hydrogenphosphate (K2HPO₄) was tested by seed soaking and by foliar application to determine whether these resistance inducers controlled root rot and vine decline of melon caused by Monosporascus cannonballus. Tests were carried out in pots and under field conditions in a two-year trial. Application of MeJA to melon seed significantly reduced symptoms of melon root rot and vine decline in soil artificially inoculated with M. cannonballus, and seeds treated with BTH and K2HPO₄ produced plants with a slightly greater resistance to the pathogen. Greenhouse experiments in soil naturally infected with M. cannonballus in 2006 showed that MeJA treatments by seed soaking followed by foliar applications decreased the severity of the disease. In 2007, both MeJA and BTH significantly reduced root rot and vine decline, but K2HPO₄ was ineffective. The resistance inducers differentially induced the synthesis of a number of pathogenesis related (PR) protein isoenzymes, markers of induced resistance in the root system. Using MeJA to induce resistance to root rot and vine decline of melon caused by M. cannonballus may provide a practical supplement to an environmentally friendly disease management when it is combined with appropriate integrated agronomic practices.