Diseases of Bluestem

Purple spot
Causal organism: Curvularia cymbopogonis (Dodge) Groves et Skolko, Imperfect fungi


Rust
Causal organism: Puccinia cesatii Shroet, Basidiomycotina

Diseases of Rhodesgrass

Bipolaris leaf spot
Causal organism: Pseudocochliobolus australiensis Tsuda et Ueyama (=Bipolaris australiensis (Ellis) Tsuda et Ueyama), Ascomycotina
Fungal disease that causes spots on leaves. The lesions are brown, capillary-shaped and produced all over the leaves. If the lesions were produced on the midrib, the width may broaden to about 1mm wide.


Curvularia leaf spot
Causal organism: Pseudocochliobolus verruculosus Tsuda et Ueyama (=Curvularia verruculosa Tandon et Bilgrami, Ascomycotina
Fungal disease that causes spots on leaves. The disease occurs in Okinawa Prefecture, the most southern region of Japan. The lesions are brown, short-stripe shaped, 1-2mm long and the damage is severe.


Leaf blight
Causal organism: Cochliobolus chrolidis Alcorn, Ascomycotina
Fungal disease that causes spots on leaves. The lesions begin to expand from the leaf edge and become 0.3-0.5 cm wide. It elongate along the leaf vein and produce dense mycelial mass on the surface.


Summer blight
Causal organism: Rhizoctonia solani Kühn, Basidiomycotina
Ash green and water-soaked lesions appears at first and the whole infected plant soften like being boiled before long. Then, the infected stalks and leaves fall one upon another and rot when the disease progresses and hyphae like spider' web appear covering all the infected part. Later light brown to brown sclerotia of about 5mm in diameter are produced on the infected part. At this point, the infected grass withers forming patches and the grassland gradually becomes bare land. The causal organism is polyxeny and can infect most grasses and legumes of herbage.

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