SPORULATION OF BIPOLARIS-SOROKINIANA ON THE CROWNS OF CROP PLANTS GROWN IN SASKATCHEWAN

Production of conidia by B. sorokiniana was determined on crowns of fi eld-grown annual crops in the fall of each year from 1991 to 1993. Spo rulation was highest on crowns of the annual cereal crops, barley, can ary seed, rye, triticale, oat, and wheat. Sporulation varied from year to year with the highest numbers in 1992 and the lowest in 1993. Ther e were differences between cultivars of wheat and of barley, but the d ifferences were not consistent from year to year. Significantly lower conidial numbers occurred on annual pulse crops (fababean, field pea, lentil), and oilseed crops (canola, flax, mustard, safflower, sunflowe r) than on cereal crops. In 1992 and 1993, sporulation was assessed on perennial forage legumes and grasses. Sporulation was significantly h igher on wheatgrass species (crested, intermediate, northern, slender, streambank, tall, and western wheatgrass) than on other forage grasse s (smooth bromegrass, meadow bromegrass, reed canarygrass, Altai wildr ye, Dahurian Wildrye, and Russian wildrye) and forage legumes (alfalfa , alsike clover, birdsfoot trefoil, cicer milkvetch, red clover and sa infoin). The low sporulation on crowns of annual pulse crops, annual o ilseed crops, forage legumes, and forage grasses other than on wheatgr ass species indicates their suitability in crop rotations designed to reduce the inoculum density of B. sorokiniana. Growing annual cereal c rops and wheatgrass forage grasses will likely maintain or increase th e inoculum levels of B. sorokiniana in soil.