Stem rust

It is characterised by pustules (a pimple-like or blister-like structure) that develop and break through the surface of the stems, leaves, sheaths, chaff and beards of the wheat plant. The kernels are badly shrivelled, many of them being so light and chaffy that are blown out with chaff in threshing. The remaining grains may be shrunken to one-half or two-thirds normal size. Myriads of brick-red spores escape from the pustules and are carried by the wind to other wheat plants. Wheat stem rust also attacks barley, occasionally rye and many wild grasses (Hordeum spp., Agropyron spp., Elymus spp., Hystrix spp. and some brome grasses). It does not attack oats.