Efficacy of methyl iodide soil fumigation for control of Meloidogyne incognita, Tylenchulus semipenetrans and Heterodera schachtii

Sigmoidal dose-response curves were derived for Meloidogyne incognita, Tylenchulus semipenetrans, and Heterodera schachtii treated with methyl iodide or methyl bromide under laboratory and field conditions. Laboratory dose-response experiments were conducted in 1.9 dm(3) fumigation jars in three soil types. Field experiments were conducted in a San Emigdio sandy loam and a Carsetas loamy sand previously infested with M. incognita. Muslin sample bags containing either roots or soil infested with T. semipenetrans and H. schachtii were buried in each field plot. M. incognita was bioassayed on tomato roots and survival of other nematodes was assayed by Baermann funnel extraction. A comparison of the methyl bromide: methyl iodide ratios at the EC(ED)(90) rates indicated that, averaged over all treatments, methyl iodide was 4.67 and 1.77 times more potent than methyl bromide in laboratory and field experiments, respectively.