MANAGEMENT OF THE TOBACCO BLACK SHANK-ROOT-KNOT COMPLEX WITH COMBINATIONS OF SOIL FUMIGANTS AND METALAXYL

When applied preplant incorporated and at last cultivation (lay-by), 1 ,3-dichloropropene (1,3-D) at 56 L/ha, 1,3-D/17% chloropicrin (C-17) a t 65.5 L and 93.5 L/ ha, and fenamiphos at 6.7 kg Li./ha + metalaxyl a t 0.56 kg a.i./ha were equally effective in reducing tobacco black sha nk on cultivars K-326, Speight G-70, and Coker 371 Gold. Methyl bromid e at 112 kg/ha injected into the soil prior to transplanting was not e ffective in reducing black shank but reduced damage from root-knot nem atodes in all cultivars. All treatments reduced final root-gall indice s compared to the untreated control in 1990 and 199 1. In 199 1, final root-gall indices were higher for Coker 371 Gold, a cultivar with no resistance to Meloidogyne incognita, than for Speight G-70 or K-326, c ultivars with resistance to M. incognita. Yields were increased over t he untreated control by 1,3-D/C-17 treatments at either rate for all c ultivars in both years. Yields were higher with 1,3-D/C-17 than with o ther treatments in 1990 and higher with fenamiphos treatments in 1991 for K-326 and Coker 371 Gold. Yields for K-326 were usually higher tha n those for the other cultivars in all treatments both years.