Integrated management of sudden wilt in melons, caused by Monosporascus cannonballus, using grafting and reduced rates of methyl bromide

Sudden wilt of melons induced by Monosporascus cannonballus is a worldwide problem, mainly in arid and semi-arid regions. Soil disinfestation by fumig ation with methyl bromide is a common and very effective treatment for dise ase control. However, methyl bromide is expected to be banned from use with in the next 5 to 10 years; therefore, alternative measures for disease mana gement are urgently needed. In this study, the efficacy of methyl bromide a t a reduced rate (15 g/m(2) instead of 50 g/m(2)) and grafted plants, alone or in combination, was examined. Experiments were conducted in the 'Arava region in southern Israel in naturally infested fields. First, various root stock accessions were tested in three experiments. Of the eight rootstocks evaluated, cv. Brava (Cucurbita maxima) was selected to serve as a rootstoc k in the subsequent experiments due to its effects on wilt reduction (63 to 100% reduction in two experiments and 35% reduction in one experiment) and its horticultural performance. Next, integration of grafting and a reduced rate of methyl bromide was tested in two experiments. The reduced methyl b romide rate suppressed disease, but results were variable (32 and 91% reduc tion in the two experiments). Grafting, when used alone, significantly redu ced wile incidence by 84 to 87% compared to untreated plots. Integration of the two control measures provided adequate and reliable results and wilt i ncidence was always significantly lower (75 to 100% reduction) than inciden ce in untreated plots. Because control by each measure alone varies, integr ated application is preferable.