Influence of the Tobacco Cyst Nematode (Globodera tabacum) on Fusarium Wilt of Connecticut Broadleaf Tobacco. J. A. LaMondia, Connecticut Agricultural Experiment Station, P.O. Box 1106, New Haven 06504. G. S. Taylor, Connecticut Agricultural Experiment Station, P.O. Box 1106, New Haven 06504. Plant Dis. 71:1129-1132. Accepted for publication 20 June 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-1129.

The influence of Globodera tabacum on wilt of broadleaf tobacco caused by Fusarium oxysporum was examined under field microplot and greenhouse conditions. At high inoculum densities, F. oxysporum alone readily killed plants regardless of G. tabacum infection, but at lower F. oxysporum densities, G. tabacum densities above about 25 juveniles per cubic centimeter of soil increased wilt in tobacco both susceptible and resistant to Fusarium. The nematode alone did not cause wilt symptoms. Fusarium wilt symptoms on resistant tobacco lines were much less severe than on susceptible lines, despite the fact that F. oxysporum was isolated from stems of up to 80% of resistant plants. In a split-root system experiment, G. tabacum increased wilt in a localized rather than systemic manner. These data suggest that the incidence of Fusarium wilt in production fields can be decreased by reducing G. tabacum populations below threshold levels.