Management of root-knot nematodes and nutsedge with fumigant alternatives to methyl bromide in North Florida U.S.A. tomato production

Abstract

Four field trials were conducted to determine efficacy of soil fumigant alternatives to methyl bromide for control of root-knot nematodes (Meloidogyne spp.) and nutsedge (Cyperus spp.) in tomato. Chemical treatments, rates, and combinations varied but generally included 1,3-dichloropropene (1,3-D), methyl bromide, metam sodium, dazomet, and chloropicrin (Pic). The herbicide pebulate was applied to all treatments except methyl bromide and the controls to provide suppression of nutsedge. Black polyethylene mulch and drip irrigation tubing were laid concurrently with or immediately after chemical application. Data collection in the tests included fruit yield, root gall indices, second-stage root-knot nematode juvenile (I2) numbers and nutsedge populations. Methyl bromide, methyl bromide + Pic, and 1,3-D + Pic produced greatest reduction in root galling and J2 population densities in these tests while the dazomet and metam sodium treatments provided variable reductions. Nutsedge population densities were reduced by 1,3-D + Pic + pebulate, Pic + pebulate and the methyl bromide treatments. Dazomet + pebulate and metam sodium + pebulate provided intermediate reductions in nutsedge population densities. Average tomato yields across trials and among treatments mirrored root galling, second-stage juvenile numbers and nutsedge population densities. Mean yields for methyl bromide, 1,3-D + Pic, Pic, dazomet (high rate), metam sodium (high rate), and the control were 58, 54.2, 49.5, 50.8, 51.7, and 50.3 mtlha. Data from these tests indicated that soil treatments with 1,3-D + Pic provided greatest control of root-knot nematodes and nutsedge and produced higher average tomato fruit yields compared to the other methyl bromide alternatives and rates tested.