Recently, a problem has developed in Hants County, Nova Scotia, Canada. The weed species common St. Johnswort (Hypericum perforatum L.), has become established in areas of West Hants County. It had previously been found along roadsides and ditched embankments, but it has now made its way into established pastures. On June 13, 1987, a local beef producer reported a case of photosensitization from grazing common St. Johnswort in one of her nurse cows. No prior cases had been reported in the province, although a neighboring farmer had lost cattle in the previous two years. This sparked the concern of farmers and agriculture representatives in the area as to the potential problem from this weed.