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The representative fungal disease causing plant death in the warm region. The hyphae like white cotton twine bristly around the base of the stalk and crown as the temperature goes up after the end of the rainy season. The infected tissues gradually brown, collapse, and then the entire upper-ground part withers. The hyphae become like the bunch on withering leaf and stalk, and then becomes yellowish brown sclerotia. They overwinter in the soil and become the disease spreader of next year. The thatch of the infected tissue, sclerotia and the fragment of hyphae disperse and transmit by wind and rain. The causal organism is more polyxeny than Sclerotinia crown and stem rot fungi.
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Fungal disease causing stem and plant rot at the early spring. It spreads violently in the cool and wet conditions. Black to blackish brown lesions of various sizes appears at first from the lower leaves and then extend to the stalks and petioles. The lesions on the leaf fuses and become large. The leaf turns to yellow and falls at last. When the disease advances, many stalk and petioles become blackish brown and wither. Black small grains (pycnidia) are formed on the lesion and the spores disperse under the wet condition by wind and rain. The spores are occasionally carried by insects attaching them to the body. The causal organism mainly infect alfalfa, but they can infect also clovers and beans, etc. by inoculation.
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Spot-causing fungal disease occurring in leaf. The lesions are grayish brown with dark brown border, small spots in the leaf. Then the border changes into faint brown and the lesion expands to a round one of about 3-5 mm with an indistinct brown zonation. The lesion often extends from the leaf rim, fuse with the adjacent lesion, and becomes large. The leaf shrinks and withers in results. The diseased leaf defoliates at the early stage. The species of the causal organism is same with leaf blight fungi of red clover, but the pathogenicity is differentiated. |
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An Important fungal disease which occurs all over the country and becomes a cause of summer depression of grassland. 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. AG-1 IA and IB of R.solani cause the disease. |
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Important fungal disease which causes plant death and occurs mainly in Hokkaido Dist. The symptom appears just after snow-melting. Stems and leaves become water-soaked and softened like boiled. When they are dry, they discolor to ash brown. Dark brown to black, globular to irregular sclerotia of 0.5-1mm in diameter are produced on them. The biotype A is reported to infect legumes. |
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Fungal disease causing plant death and large damage occurring in Hokkaido and Kanto Dist. At first, the lower leaves begin to wilt and gradually become yellow and fall. The new stalks repeatedly wither and the whole plant wilt finally. In root, the vascular bundle is invaded and become black. Therefore, the plant wilts because of the short of water absorption. The part of crown is covered by gray molds. The molds are the cluster of conidia and they drops in the soil and disperse in the high soil moisture condition. The causal organism can infect many kinds of weeds by inoculation, but the kind of weed which can be a disease spreader in nature is not yet confirmed in Japan. |
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Fungal disease causing plant death. In early summer, young leaf begins to wither from leaf tip. And soon, all the leaves come to wither and die in brown. The main root is covered with purple hyphae like felts and the inside of the root rots. Purplish red sclerotia of about 1mm in diameter are occasionally produced on the surface of the infected root. The causal organism is very polyxeny and infect not only many legume crops but also fruit trees. |
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Fungal disease which causes wilting of plants occurring in Hokkaido. At first, the leaf turns to yellow and withers at the tip, then the disease advances to the entire stalk gradually. The development of the secondary root becomes bad and the center part of a tap root turns brown from crown to root tip at this time. When the disease advances, the infected plant becomes difficult to regenerate, weakens and withers. This causes the decline of grasslands. The causal organism can also infect red clover. It is reported that the occurrence are more frequent in volcanic ash soil than in the alluvial soil.
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Spot-causing fungal disease occurring in the leaf. The leaf fades somehow at first and yellow blotches of irregular shapes and about 5mm in size appear gradually. Small black grains appear in the center of the lesion, and then the lesions turn to brown and fuse mutually. The entire leaf withers in getting rolled up at last. |
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Most common nutrient deficiency of alfalfa often occurring under wet and rainy conditions. Firstly white small sots appear on the lower leaves and then those will appear also on the upper leaves. When the symptoms progress, borders around the spots turn yellow, resulting blackish brown necrosis on the leaves. If occurring severely, it causes death of the plants, decrease of overwintering rate and grass vigor, resulting the decrease of the legume ratio in grasslands. Timely diagnosis of the soil nutrient and adequate fertilizer application are important to prevent the symptom. |
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