Recurrent Selection Performance for FOV Race 4 Resistance in Selected Germplasm and Progeny

Recurrent selection is being used to improve Fusarium oxysporum f. sp. vasinfectum race 4 (FOV4) resistance in Upland (Gossypium hirsutum) and Pima (G. barbadense) cotton using naturally infested fields and artificially inoculum-greenhouse sites.  Germplasm lines with known FOV4 resistance were selected and crossed within and with a diverse set of lines to develop new progeny. These entries were exposed to FOV4 pressure in naturally infested FOV4 fields and rated. Entries were then selected, self-pollinated and cross pollinated.  Parental lines and F₁ populations were then inoculated with FOV4 and grown under greenhouse conditions for rating and reselection. The performance of several reselected entries, parental lines and F₁ populations over a three year period will be summarized and presented.