Dimethyl Disulfide (DMDS): a New Soil Fumigant to Control Root-Knot Nematodes, Meloidogyne spp., in Protected Crops in Sicily, Italy

Dimethyl Disulfide (DMDS), as an EC formulation, was applied via drip-irrigation to control the root-knot nematode Meloidogyne incognita in two trials in protected crops. The trials were carried out in Sicily (Italy) during 2012 on melon and on tomato, according to a randomized block design with 4-5 replicates per treatment. The soil of the sites was sandy and naturally severely infested by the nematode. DMDS was applied at the rates of 300, 400, and 500 kg/ha (the last rate only in tomato). The soil was covered with virtually impermeable film (VIF) before fumigation and uncovered 2 weeks later. DMDS treatments were compared with 1,3-dichloropropene (140 L/ha for melon and 180 L/ha for tomato) and a non-treated control. Yield was recorded in all trials. The nematode attack on the roots was evaluated according to the 0-10 Zeck's scale modified (0 no galls and 10 root system completely deformed by large and numerous galls). In the melon trial, 60 days after transplanting (DAT), both DMDS doses (400 and 300 kg/ha) showed low root gall indices (1.2 and 1.5, respectively), compared to the non-treated control (5.5) and 1,3-dichloropropene (4.2). In the tomato trial 120 DAT, DMDS at 500, 400 and 300 kg/ha showed root gall indices of 2.9, 2.7, and 3.0, respectively, compared to 9.6 of the non-treated control and 3.6 of 1,3-dichloropropene. All nematicidal treatments significantly increased marketable yields of melon and tomato in comparison to non-treated controls. Therefore, DMDS, once registered, could be a new effective solution to control root-knot nematodes in protected crops and because of its favourable ecotoxicologial profile, it could also be considered for IPM programmes of protected crops.