Fungicidal control of foliar diseases of white lupin (Lupinus albus)

A range of fungicides was tested against rust (Uromyces lupinicolus) and brown spot (Pleiochaeta setosa) on autumn-sown white lupin (Lupinus albus) in three experiments in harvest years 1995, 1997 and 1998. Rust was severe in all three years but did not develop in an additional experiment in 1996. Brown spot occurred only in 1997 and 1998 when natural inoculum was augmented by an artificial source and weather conditions were favourable for inoculum dispersal and disease development. Tebuconazole was the only fungicide tested that controlled rust consistently, whereas iprodione + thiophanate-methyl, tebuconazole and prochloraz each decreased the severity of brown spot. Yield increases in 1997 and 1998 were thought to be attributable mainly to control of rust. Fungicides were most effective when applied as soon as symptoms were observed. Two applications of an effective fungicide generally controlled disease more than a single application; a third application gave no additional benefit. (C) 1999 Elsevier Science Ltd. All rights reserved.