Black shank resistance in air-cured tobacco - South Africa
In the South African air-cured tobacco producing regions, black shank, caused by Phytophthora nicotianae var. nicotianae, is a major concern. The control of this disease is based only on crop rotation and chemical control by means of metalaxyl derivates. However these products are registered on flue-cured and not on air-cured tobacco. For the past 40 years, the air-cured tobacco producers planted only one dark air-cured cultivar, CDL 28. Although high yielding and delivering tobacco of very good quality, it has no resistance to black shank.
A new dark air-cured tobacco cultivar, LD2, with high resistance to Phytophthora nicotianae var. nicotianae, has now been released by the Agricultural Research Council of South Africa. This cultivar originated from back crossings of C11, WOSB, Irrabourbon and CDL28. After seven generations of inbreeding, it has attained homozygosity for the much needed black shank resistance as well as other desirable characteristics.
LD2 was tested over five seasons and in all dark air-cured tobacco production regions in South Africa. The cultivar was found to be widely adapted with acceptable yield, quality, income as well as total nitrogen, total alkaloids and reducing sugar concentrations. LD2 yields higher than CDL28, the current South African standard.