TIME OF APPLICATION AND WINTER-WHEAT GENOTYPE AFFECT PRODUCTION OF LARGE SEED AFTER FUNGICIDE APPLICATION

Two field experiments were established to compare four times of fungic ide application (flag leaf emergence, boot, fully headed, and milky ri pe) for improving production of large seed. Quadratic models fit the d ata when large-seed (greater than or equal to 0.238-cm diameter) yield s were regressed against time of fungicide application. The optimum ti me to apply foliar fungicides. was between boot and fully headed. Four other field experiments were established to compare large-seed yields after fungicide application on 12 cultivars differing in susceptibili ty to foliar diseases. With moderate foliar disease pressure, linear m odels fit the data when increases in large seed due to fungicide were regressed against Kansas Cooperative Extension Service disease ratings . In conjunction with the expected price of seed wheat, these models c an be used to help decide whether foliar fungicide is warranted.