EFFECT OF MALE-STERILITY ON ERGOT DISEASE SPREAD IN WHEAT

Cytoplasmic male-sterile winter wheat. grown in the field in England w ith a limited supply of pollen, set over 80% less seed than fertile wh eat. Wheat ears precociously inoculated with ergot (Claviceps purpurea ) initiated local natural epidemics of disease at flowering and, withi n 1.5 m of primary foci, sclerotial abundance at harvest was correlate d inversely with seed set. Sclerotial mass in poorly pollinated male-s terile wheat comprised more than 20% of the threshed grain yield, in c ontrast to only 0.7% in fertile wheat.