Target spot disease in tobacco has developed into an economically important disease of the crop over the past 20 years. In 2005, Quadris got a Section 18 label for emergency use from late June to mid-October, but researchers are scrambling to find a more long-term and less expensive management tool.
Chuck Jones, a pathologist at the Southern Piedmont Research and Extension Center in Blackstone, Va., is working with geneticists Beth Grabau and John Jelesko at VPI's main campus in Blacksburg, Va., to develop a genetically enhanced tobacco variety, with built in resistance to target spot.
The barley oxalate oxidase, or BOO gene used to develop target spot resistance in tobacco plants is also being used to produce peanut varieties resistant to sclerotinia blight, an economically debilitating disease of Virginia type peanuts.
Plants of the popular burley tobacco cultivar TN 90 and flue-cured cultivar K 326 have been transformed to contain the BOO gene. Each variety has been transferred from the lab in Blacksburg to the field in Blackstone and will be evaluated for disease resistance characteristics.
Improved resistance to target spot would improve yields for tobacco producers without increasing the expense of growing a crop, sometimes toxic residues in these crops, and potential environmental problems associated with use of pesticides.
In peanuts, the 2006 crop will be the fourth crop grown in the field. So far, these experimental varieties of the BOO-containing peanut plants have shown excellent yields and excellent resistance to sclerotinia blight.
The Virginia Tech researchers are already looking at double stacking disease resistant genes in both peanut and tobacco varieties. The 2006 crop will be the fourth year of field testing for peanut varieties containing BOO genes for sclerotinia resistance.
At best BOO-containing peanut varieties are three or four years away, and tobacco varieties even further in the future. Beth Grabau, head of the plant pathology program at Virginia Tech and the mastermind behind the genetic inclusion of the disease-blocking oxalates into peanut and tobacco plants, says the progress is exciting, and by scientific standards moving rapidly.