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Typical viral disease. Most individuals are infected at the second or third year from seeding in the warm regions. The symptoms begin to appear in spring and are various such as yellow mosaic, green mosaic, chlorotic spots, rugose, etc. according to the varieties of plants and environmental conditions. The virus is transmitted by sucking of the various aphids. The main ones of the causal virus are AMV and BYMV. The strains of the virus can be roughly estimated by the symptom. |
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Fungal disease occurring in the entire upper-ground part. The lesions are blackish brown and irregular shaped ones in the leaf. They soon fuse mutually and become large lesion which covers the whole leaf. The black and fluffy sclerotia are produced in the center part of the lesion. Black hyphae extends to the entire plant when occurring severely and cause plant death. The causal organism produces the alkaloid, suraflamine, which causes goat's slaver disease. |
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Fungal disease which produces spots in the leaf. The lesions at first appear as yellow discolored parts, and soon they turn to brown and become characteristic V letterform lesions devided by the leaf vein. When the petiole is infected, the leaf withers and are killed soon. When occurring severely, the whole plant looks like burned and the yield decreases much. Damage is large in younger leaves than old ones. It occurs severely when the temperature increases considerably after the rainy season. The pathogen infects other clovers. |
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Fungal disease mainly occurring in stalk, petiole and spikelet. The lesions are black brown, spindle shaped, 1-3 cm in length. They often sink in the center part and the leaf tears from the part. The causal organism prefers the cool and wet conditions and is occurring mainly in Hokkaido in spring and autumn. |
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Fungal disease which makes plants white powdery. White, thin and indistinct colonies like sprinkled white powder are produced on the surface of the leaf in the early spring. They gradually become thick, cover the whole leaf and cause leaf blight. The disease occurs severely in the cool and dry condition, and the damage becomes large when sunshine is insufficient under the cloudy weather. The damage is not so large not like in red clover. The causal organism can infect other legumes. |
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Important fungal disease which causes plant death occurring in cool and wet regions. The small spots appears at first and then the leaf and stalk turn to yellow and wither. The disease progresses gradually under the snowfall. The stem, leaf and root rot to ash white according to increase of the temperature after snow-melting in the spring of next year. White and fluffy hyphae are produced on the surface of the withering plant and large black sclerotia of irregular types and about 8-10mm in size are produced before long. They germinate in autumn and produce light brown stroma of 3-8 mm in diameter. The ascospores spread from the stroma and the infection happens again. The host range of the causal organism is wide including alfalfa and vetches. |
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Fungal disease which produces spots in the leaf. It occurs mainly in the rainy season and autumn. The lesions are at first small and drab to brown ones. Then they expand gradually and become brown to dark brown lesions of about 5-10mm in diameter with characteristic zonations. The species of the causal organisms is same with Stemphylium leaf spot fungus in red clover. |
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Spot-causing fungal disease mainly occurring in leaf and stalk. In leaf, the ash brown lesion which is divided by leaf vein is produced and fuses to each other, causing leaf blight. It becomes the purple brown stripe when occurring in the stalk and the damage grows further. The causal organism can invades other clovers, but the pathogenicity is considered to be differentiated in some extents. |
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