Management of Macrophomina wilt in melons using grafting or fungicide soil application: Pathological, horticultural and economical aspects

Melon cultivation in the Yizre’el Valley of northern Israel is threatened by plant wilting that occurs toward harvest. Macrophomina phaseolina is the most common fungus isolated from the wilted plants. Disease management using grafted plants or soil application of fungicides to non-grafted melons during the growing season was studied. For the grafting experiments, two Ananas-type melons (Cucumis melo L.), cv. 6405 and Eyal, were grafted onto interspesific F1Cucurbita rootstock TZ-148 and transplanted at spacings of 60, 90, 120 and 180 cm within rows in M. phaseolina infested soil to test their ability to cope with the disease and to evaluate the profitability of grafted plant cultivation at different spacings. Grafted plants did not wilt, compared to 80 and 70% wilting of non-grafted melon plants in experiments conducted in 2006 and 2008, respectively. Cultivation of grafted melons in infested soil for the local market was shown to be profitable, even with a 50% reduction in transplant number for a given area (120 cm between transplants). In addition, selection of the right melon cultivar as scion was shown to be crucial to the success of the crop. In another set of experiments conducted in summer 2010 with non-grafted melon plants, application of the fungicides azoxystrobin alone or combined with chlorothalonil or medenoxam reduced disease incidence to 5% as compared to 45% in the untreated control. Disease management using both cultural and chemical approaches is discussed.

► Melon grafted onto Cucurbita rootstocks did not wilt in Macrophomina phaseolina infested field. ► The yield of grafted melon was higher as compared to non-grafted ones. ► Melon yield of the grafted melon was not negatively affected by a reduction in plant number per given area. ► The fungicide azoxystrobin, alone or combined with chlorothalonil or mefenoxam, reduced Macrophomina wilt.