Efficacy of Metam Sodium Under Drip and Surface Spray Application in Florida Tomato Production

The most effective soil fumigant for the past 40 years for preplant chemical control of nematodes, weeds, and fungal pathogens in Florida vegetable production has been methyl bromide (MBr). Unfortunately, MBr has been implicated in depletion of stratospheric ozone, and is slated to be banned in the United States. A possible alternative replacement to MBr is metam sodium (MS, sodium N-methyl dithiocarbamate). However, previous field trials have reported inconsistent pestpathogen control efficacy. The objective of the present study was to compare the effectiveness of MS applied via drip irrigation versus surface spray application followed by soil incorporation on pest-pathogen control and tomato (Lycopersicon esculentum Mill.) production. Two field tests were conducted at the Plant Science Research and Extension Unit, Citra, Florida to compare these MS application methods to conventional MBr soil fumigation. The average total marketable tomato yield from pre-plant MBr fumigation from the two field trials was 79,800 kg ha. Control plots resulted in significantly lower yields than that of MBr, ranging from 15,900 to 53,700 kg ha. Although total yields from MS fumigation was not significantly different than that of MBr, total marketable yields were suppressed with 64,000 kg ha under drip irrigation and 70,800 kg ha under surface sprayed MS fumigation practices followed by soil incorporation. Results from these studies show the difficulty in pest-pathogen control for MS use in Florida sandy soils, as root-knot nematode and nutsedge weed problems continued to hinder tomato crop production relative to yields observed under MBr shank soil fumigation.