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Yield/Quality Trade-Offs of Tobacco Mosaic Virus-Resistant Tobacco Cultivars in Relation to Disease Management. C. S. Johnson, Graduate Assistant, Department of Plant Pathology, North Carolina State University, Raleigh 27650. C. E. Main, Professor, Department of Plant Pathology, North Carolina State University, Raleigh 27650. Plant Dis. 67:886-890. Accepted for publication 21 January 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-886.

Field tests were conducted at two locations for 2 yr to quantify differences in flue-cured tobacco yield, quality, and value among tobacco mosaic virus (TMV)-resistant and -susceptible cultivars. Disease incidences (percent plants infected) were determined at a level at or above which resistant cultivars could be considered as a management option to reduce expected losses from planting susceptible cultivars. Incidence thresholds observed represented economic trade-off levels that may assist farmers in decisions regarding management of crop losses caused by TMV. Recently developed TMV-resistant cultivars had poorer leaf quality but produced as much or more yield and dollar income than most uninfected TMV-susceptible cultivars. Yields and values of a representative TMV-resistant cultivar were equivalent to that of a widely grown susceptible cultivar at TMV incidence levels in the susceptible cultivar of 13 and 37%. Using resistant cultivars could be recommended as the best tactic for managing tobacco mosaic when the incidence of the disease exceeds these levels. The apparent discrepancy between the yield and value thresholds was caused by reductions in leaf quality linked with the TMV resistance factor. Loss in quality could not be attributed solely to any single component of government tobacco grades or physical characteristic of flue -cured leaves.

Keyword(s): crop loss assessment, modeling.