TABLE CONTENTS

SESSION FORTY-NINE – COMMERCIAL PRODUCTS AND
PROCEDURES FOR SOIL DISINFESTATION AND NEMATODES
CONTROL
CONVENORS: NANCY KOKALIS-BURELLE & INGA ZASADA
Chemical Alternatives to Methyl Bromide for Field-Grown Ornamental
Crop Production in Florida
Kokalis-Burelle, N. (1), E.N. Rosskopf (1) & R. McSorley (2)
(1) USDA, Agricultural Research Service, U.S. Horticultural Research Lab, Ft. Pierce, FL, 34945; (2)
Department of Entomology and Nematology, University of Florida, Gainesville, FL, 32611
Identification of alternatives to methyl bromide for field-grown ornamental crops in the U.S.
is particularly challenging because of the need to control rogues (off-varieties), limited
availability of labeled materials, difficulty gluing wide sheets of virtually impermeable films
for broadcast fumigation, and the proximity of occupied structures to production areas.
Numerous commercial and experimental field trials were conducted under a range of
nematode, weed, and pathogen pressures in southeastern and south central Florida to evaluate
broadcast applications of Midas (iodomethane:chloropicrin 50:50), and Paladin
(dimthyldisulfide (DMDS): chloropicrin 79:21). Crops included snapdragon (Antirrhinum
majus), celosia (Celosia argentea var. cristata), sunflower (Helianthus annuus), delphinium
(Delphinium elatum), and caladium (Caladium hortulanum). Overall, both Midas and Paladin
provided nematode and weed control comparable to methyl bromide (MeBr) with no
significant phytotoxicity observed in any of the crops tested. Immediately following
treatment, both compounds reduced Meloidogyne spp. juveniles in soil as well as MeBr, and
recolonization often occurred more slowly in Midas treatments compared to MeBr.
However, under subtropical conditions and high nematode pressure, parasitic nematodes
rebounded to similar levels in all treatments by 10 weeks after fumigation. Interestingly,
Midas and Paladin allowed for faster recolonization of soil by microbivorous nematodes than
MeBr. In caladium, a long-season crop (10 months), no differences in nematode control were
observed among the three fumigants by the end of the season. However, Paladin resulted in
lower total yield than MeBr. Application of Midas and Paladin requires more oversight and
precision because these compounds are much less volatile than MeBr, and therefore do not
move as well through the soil. Future research on chemical alternatives for this industry will
focus on three new compounds, citroxin, ethanedinitrile, and 2-bromoethanol, which have
demonstrated potential for control of Meloidogyne spp., weeds, and pathogens.
5 th International Congress of Nematology, 2008 179