Control of Globodera tabacum solanacearum by Rotating Susceptible and Resistant Flue-Cured Tobacco Cultivars

Abstract

Alternate planting of flue-cured tobacco cultivars resistant (NC 567 or Speight G-80) or susceptible (K 326) to the tobacco cyst nematode (TCN) Globodera tabacum ssp. solanacearum on 1-year or 2-year intervals was investigated in Virginia in 1987-89. The TCN-resistant cultivars reduced TCN population densities compared with continuous planting of K 326. Initial TCN egg densities in soil tended to be lower and yields of K 326 without fenamiphos were consistently higher when a resistant cultivar had been planted the previous year. Planting NC 567 in 1987-88 reduced initial 1989 TCN densities to below 1,000 eggs/500 cm³ soil. Use of NC 567 in 1987-88 also increased 1989 yields and net economic returns for K 326 above those of untreated plots continuously planted with K 326. Yields and net economic returns were similar from cultivar rotation strategies involving Speight G-80 or NC 567. Average yield and net economic returns for 1987-89, however, were significantly increased by use of fenamiphos with K 326 but not by any of the cultivar rotation strategies. Key words: fenamiphos, Globodera tabacum solanacearum, nematode management, Nicotiana tabacum, resistance, tobacco, tobacco cyst nematode.