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Fungal disease which causes plant withering under snowfall and distributes in the northern area of Japan. Stem and leaf under snow soften, wither, and look pink. The sclerotia are not formed. As for the turf in non-snowfall region, the occurrence is reported. The causal organism is known to produce nivalenol and deoxynivalenol as mycotoxins, but the Japanese isolates were elucidated not to produce them by recent researches.
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New disease firstly occurred in Miyazaki Pref., the southern part of Japan. The lesions are at first small and white to gray moldy in the leaf and sheath appearing from April to July. When the disease advances, the entire plant body looks like being covered with white powders. This white powders are conidia and they disperse by wind and rain. The host range of the pathogen is restricted to ryegrass (Lolium spp.). |
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New disease firstly occurred in Tochigi Pref., the central part of Japan, in 2006. Upper-ground parts of diseased plants yellow, wilt and killed with roots and crowns discoloring brown to black. When the temperature keeps high after sowing in September to October. The disease was already reported as a turfgrass disease caused by P. aristosporum, P. vanterpoolii and P. myriotylum, but P. spinosum and P. sylvaticum were first reported in ryegrass in Japan. |
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Spot-causing fungal disease occurring in spring and autumn. The lesions are at first water-soaked small spot, and then become faint orange to ash white with brown border, long spindle to lens shape, 0.5-2cm in length, characteristic lesions. The lesions fuse gradually and becomes cloud-shaped ones. The infected leaf often tears from the lesion part. The infected plants withers producing a patch and the grassland looks white when occurring severely. The disease occurs severely under the cool and wet condition. The species of the pathogen is same with that of barley scald, but the pathogenicity is differentiated. |
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Important fungal disease which causes plant death in Hokkaido and Tohoku Dist. The disease distributes in the region where the frozen period of soil is long. The entire plant becomes water-soaked and discolors to deep green and softened immediately after snow-melting like boiled. It becomes ash brown when drying and black, large sclerotia of 5-10mm in size like the excrement of rat are formed on the surface. Stroma come out from the sclerotia at late autumn and disperse ascospores as inoculum sources. The causal organism is polyxeny and barley, wheat, fescue, ryegrass, timothy, redtop, and etc. are reported to be infected. Orchardgrass and ryegrass are the weakest grasses to the disease.
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The disease occurred in Kanto region, the central part of Japan in August 2018, and in Kyushu region, the southern part of Japan, in October 2019. The seedlings of Italian and perennial ryegrass approximately 2 weeks after seeding wither and are killed. The root surface of infected plants turns brown and the amount of roots decreases drastically with browning of basal stems of the plants. The disease occurs severely especially by early seeding from August to September when the air temperature is around 30C and soil temperature around 25C. The two pathogens are Pythium that prefer high temperature and they grow maximumly at 35C. P. aphanidermatum has stronger pathogenicity compared to P. periilum that is also known as a pathogen causing Pythium stem and root rot of corn. |
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Fungal disease occurring in the entire upper-ground part such as leaves, sheaths, stalks and crown. Leaves and sheaths near the ground become at first dark colored, water-soaked and a white hyphae like silk crawls on the surface. Chestnut brown and globular sclerotia of 0.3-0.5 mm in diameter are produced and the plant body withers as rotting from the part near the ground. |
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Fungal disease which produces rust stroma on the leaf. The occurrence is limited to a part of Hokkaido and the damage is small. The lesions are reddish brown to iron rust color, oval to sripe swellings of 1-2mm in length and 0.5-0.6mm in width. They fuse mutually and become irregular shape. The epidermis of the lesion tears when maturing and it disperses reddish brown urediniospore and spreads. From summer to autumn, the lesions becomes blackish brown and produce teleutospores and overwinters. The pathogenicity of the causal organism is differentiated from that of orchardgrass stem rust. |
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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 softens 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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Fungal disease producing lots of spots on the leaf in summer. The lesions are brown with blackish brown center, oval to irregular shaped ones of about 5-6x2-3 mm in size. When occurring a lot, it causes leaf blight. The border part of the lesion often changes to yellow a little. The causal organism is one of wide the Helminthosporium fungi with wide host range and also causes leaf spot of fescue, etc. |
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Important fungal disease which causes plant death and occurs mainly in Hokkaido, the most northern part of Japan. The symptom is similar that of T.ishikariensis, but the sclerotia formed on the surface of withering part is reddish brown and millet grain size. The sclerotia is formed on the stalks, leaves, and roots, etc. of the withering plant. The pathogen is more saprophytic than T.ishikariensis and is considered to invade after invasion of T.ishikariensis and occur mixingly with it. |
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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 pathogen is classified to three different biotypes. Biotype A and B distributes in the much and little snowing regions, respectively. Biotype C distributes in both regions. These groups are different not only in their distribution but also their pathogenicity and fertility, etc. |
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