Blueberry rust

Disease symptoms. About 10 days after a young blueberry leaf is inoculated with urediniospores, the disease appears as tiny, chlorotic (yellow) spots on the upper leaf surface. These spots later turn reddish brown and may be surrounded by a slight chlorotic halo. Uredinia are produced on the lower leaf surface, appearing as pustules that produce yellow-orange urediniospores. Yellowish orange rust pustules soon become visible scattered over the lower leaf surfaces. There may be anthocyanescence (reddening) of affected leaves. On heavily diseased plants, the leaves can turn brown, curl up, and drop. This defoliation is the principal direct cause of harm to the plant, depriving it of its photosynthetic surfaces. The indirect effect of leaf loss is reduced plant vigor and poor fruit production.