| Abstract: | In greenhouse experiments, broadleaf tobacco plants were inoculated with tobacco cyst (Globodera tabacum tabacum) or root-knot (Meloidogyne hapla) nematodes 3, 2, or 1 week before or at the same time as Fusarium oxysporum. Plants infected with nematodes prior to fungal inoculation had greater Fusarium wilt incidence and severity than those simultaneously inoculated. G. t. tabacum increased wilt incidence and severity more than did M. hapla. Mechanical root wounding within 1 week of F. oxysporum inoculation increased wilt severity. In field experiments, early-season G. t. tabacum control by preplant soil application of oxamyl indirectly limited the incidence and severity of wilt. Wilt incidence was 48%, 23%, and 8% in 1989 and 64%, 60%, and 19% in 1990 for 0.0, 2.2, and 6.7 kg oxamyl/ha, respectively. Early infection of tobacco by G. t. tabacum predisposed broadleaf tobacco to wilt by F. oxysporum. |
