Factors affecting winter survival of the florally determinate white lupin cv. Lucyane

Summary In a series of three field experiments with factorial design, on sites that had not grown lupins previously, sowing date was the main factor affecting over‐winter survival of autumn‐sown white lupin. In 1993, the sowing dates (23 September and 20 October) were too late to prevent much plant death in autumn and early winter, with the onset of frosts. In 1994, the sowing dates (30 August and 22 September) were early enough to prevent severe frost damage, but infestations of bean seed fly (Delia platura) occurred, more in the later than in the earlier sown crops, causing wilting and plant death. Losses were decreased where furothiocarb seed treatment was applied. In 1995, losses were greater in early‐sown (12 September) than in later sown (28 September) crops; plant death was gradual, occurring into the spring, and was apparently associated with over‐development of young shoots before an unusually long, cold winter. A chlorpyrifos spray (13 or 29 September for early or late sown plots, respectively) slightly increased survival, possibly by controlling Thrips angusticeps. Fungicides applied to seed or as sprays in late autumn had little or no effect in these experiments. In another series of experiments to test fungicides, in 1992‐93 and 1993‐94, survival was poor following late sowing (in October), but was increased by application of prochloraz in December or January, or, in 1994, by seed treatment with thiram.