Cereal Rye Stem Rust
Puccinia graminis f.sp. secalis
Dark reddish brown, large, oval or elongated pustules, full of powdery spores appear on both sides of the leaves, sheaths, stems and heads in spring. Leaf and stem surfaces appear torn from ruptured pustules.
The red brown spores will rub easily off the leaf onto your finger. The black spores at the end of the season don't rub off.
Species Affected:Barely, Cereal Rye
Biology:Requires a green host for survival and can't survive in soil or on crop residues.
Epidemics are more likely in seasons that have summer rains that allow volunteer Barley and Cereal Rye to survive over summer.
Requires warm, 15-300C, moist and humid conditions for infection.
The red brown spores are infectious whereas the black spores aren't.
New strains that are infectious on "resistant" varieties commonly occur.
Life Cycle:Origin and History:
Grain yield loss can be total.
Management and Control:Sow resistant varieties. No variety is totally tolerant so other measures should also be practised to reduce inoculum loads.
Control volunteer and out of season Barley and Cereal Rye.
Control Stem Rust in Barley and Cereal Rye crops.
Seed treatments are not effective and foliar treatments with fungicides are rarely economic.
Fungicide Resistance:None reported.
Related and Similar Species:Leaf Rust of Barley (Puccinia hordei) has smaller, lighter brown and more circular pustules that do not noticeably rupture the leaf surface and only appear on the sheaths late in the season.
Leaf Rust of Wheat (Puccinia recondita) has smaller, lighter brown and more circular pustules that do not noticeably rupture the leaf surface and only appear on the sheaths late in the season.
Stem Rust of Wheat (Puccinia graminis)
Stripe Rust of Wheat (Puccinia striiformis)
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