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Phomopsis leptostromiformis (Kühn) Bubák causes Phomopsis stem blight in narrow‐leafed lupin (blue lupine; Lupinus angustifolius L.). In southern Australia, Phomopsis stem blight appears on lupins during senescence when dark lesions and fruiting bodies develop on stems. P. leptostromiformis colonizes dead stems and produces a mycotoxin that is responsible for lupinosis in livestock that graze lupin stubble. We sought high levels of resistance to Phomopsis stem blight in wild L. angustifolius and attempted to transfer resistance to domesticated types by crossing with susceptible cultivars. Resistance was rated by estimating the proportion of mature, dry stems covered with stem blight lesions. Phomopsis stem ratings of 254 accessions of wild L. angustifolius ranged from < 1% (highly resistant) to 36% (highly susceptible) at two Western Australian field sites in 1977. Stem ratings of the wild lupins were subject to a large accession ✕ site interaction. Resistant accessions came from a range of habitats within several Mediterranean countries. Many accessions were crossed with susceptible cultivars, and F4‐derived progeny, reselected for domestic traits, were tested for resistance at up to five Western Australian sites from 1981 to 1983. Stem ratings of F4‐derived progeny ranged from 3 to 37% and susceptible cultivars from 26 to 38% when averaged across the 3 yr. Variance component estimates for line ✕ site and line ✕ year interactions were relatively small. Heritability of resistance was high (0.86‐0.92) when estimated on a line mean basis across sites in 1982. Heritability was reduced (0.49‐0.83) when estimated across years involving 1983, due to low average Phomopsis stem ratings (< 20%) in 1983, which inflated line ✕ year variance components. Resistance to Phomopsis stem blight was successfully transferred from wild to domesticated L. angustifolius.

Seed treatments using the fungicide benomyl at 1.1 and 2.2 per cent w/w protected seedling rape from infection by Leptosphaeria maculans under glasshouse conditions but in field experiments with natural infection no worthwhile control of the disease was obtained. Benomyl applied as a spray to rape seedlings in field experiments gave variable but mainly poor control At the maximum rate tried it increased yields at only three out of eight experiment sites.

A survey of Phomopsis leptostromiformis infection of lupin seed in Western Australia was carried out in 1982 and 1983. Of the samples surveyed 39% were uninfected and 16.6% had >4% infection. These values differ significantly from a previous survey between 1976 and 1981 (49 and 8.4% respectively). There was a highly significant correlation (P <0.002) between the amount of discoloured seed and P. leptostromiformis infection. Results of toxicity tests for the mycotoxin phomopsin A, assessing hepatic injury in nursling rats, strongly implicate discoloured seeds as being the most toxic. Discoloured seed had more toxin in the seed hulls than in the kernal.

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