Stem Rust of Oats
Puccinia graminis f.sp. avenae
Dark reddish brown, oval to elongated pustules, full of powdery spores appear on both sides of the leaves, sheath, heads and stems. Leaf and stem surfaces appear torn from ruptured pustules.
The red brown spores will rub off the leaf onto your finger rubbed. The black spores at the end of the season don't rub off.
Species Affected:Oats, Wild Oats.
Biology:Requires warm (15-300C), moist conditions for infection.
The red brown spores are infectious whereas the black spores aren't.
Uredospores will move in wind for hundreds of kilometres and have been collected in air at more than 2000 m above the ground.
Requires a living host for survival.
Epidemics are more likely in years with summer rains that allow oats to grow out of season.
New strains that infect "resistant" varieties occur frequently.
Life Cycle:Origin and History:
It can cause complete yield loss.
Management and Control:Sow resistant varieties. See Disease Susceptibility of Oat Varieties
Control volunteer and out of season Oats.
Control Wild Oats.
Avoid out of season plantings.
Related and Similar Species:Leaf Rust of Oats (Puccinia coronata sp. avenae) has smaller, orange, circular to oval pustules that don't noticeably rupture the leaf surface and initially appear only on the leaf and only later on the sheath.
Leaf Rust of Wheat (Puccinia recondita)
Stripe Rust of Wheat (Puccinia striiformis)
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