Combinations of Chemical Soil Fumigants for Broad Spectrum Soil Disinfestation

Although the idea of applying two fumigants with different action spectrum simultaneously is not new, a choice was made for 1,3-dichloropropene (DD) + dazomet (Basamid) and dimethyl disulfide (DMDS) + Basamid. Basic research with these combinations for their fungicidal, nematicidal and herbicidal value at full as well as at half dose rate of each component revealed synergistic activity in many cases reaching methyl bromide performance level. The experimental setup consisted of modular soil columns with packed biological test materials at different depths. Classic among the phytopathogenic fungi: Rhizoctonia solani, Sclerotinia minor and S. sclerotiorum sclerotes. Meloidogyne incognita infested soil was used for nematicidal activity check, and cress and tomato seeds for herbicidal activity and phytotoxicity check. The choice for mainly studying these target organisms is their fit in the theme of the ALTMET project on research for methyl bromide alternatives in the control of butterhead lettuce pests and diseases. Combined application of fumigants at reduced dose rates was proven to perform well under practical conditions in greenhouse and outdoor crops which is reported in a separate lecture of this symposium.