The Genetics of Blackarm Resistance .IX. The Gene-B6m from Gossypium-Arboreum.

A blackarm resistance-intensifying gone, B6m, has been transferred from Gossypium arboreum to Sakel (G. barbadense). By itself, B6m confers no resistance, but in G. arboreum it is associated with the gene B4. The G. hirsutum resistance gene, B2, is stronger than B4 when both are transferred to Sakel background. For this reason the new gone B6m is being transferred to commercial synthetic blackarm-resistant Sudan Sakel and Upland (hirsutum) types carrying B2 and B3. In these combinations B6m confers in the Sudan a resistance closely approaching immunity, and this resistance appears to be retained under Uganda conditions.