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Viral disease on Zoysia japonica and Z. matrella. Typical mosaic lesions are produced mainly on leaves from early spring to early summer. Symptoms are generally light without severe shrink or death of plants. The causal organism, Zoysia mosaic virus, is filamentous with a length of 750 nm and width of 12-13nm and transmitted by plant saps. Host plants are only Zoysia spp. and the virus can not infect other gramineous plants such as corn, rice, southern crabgrass and so on.
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Fungal disease causing leaf blight in summer. The disease produces gray, spindle-shaped lesions with brown borders in the leaves. The tips of the leaves are easy to be damaged. Many black spots (acervuli) are produced in the old lesions. |
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Fungal disease causing leaf blight in spring or autumn. The disease produces dark brown stripe of 2-5 mm in length and 0.5-1 mm in width mainly in the leaf. The leaf turns to yellow and withers when occurring severely. It is easy to occur severely when the plant body weakens by the occurrence of stripe leaf roll disease or the application of herbicide. The teleomorph of the causal organism is not found on the plant body in nature. |
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Spot-causing fungal disease occurring a lot in the north of Kanto. The lesions are ash white with dark brown border, oval to spindle shaped and about 5x2 mm in size and become to distinct rings spot. The disease occurs a lot when the plant bodies grow too thick in the nursery. It is doubtful that the causal organism belongs to the genus, Drechslera. |
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Fungal disease whose damage is largest in Japanese turf grass. The symptom is at first indistinct patch at the early spring, but the large lesion soon appears with increasing of temperature. The lesion is ash white and irregular shaped and reaches as many as 2-3 m in diameter. Regrowth of plant bodies becomes impossible if the treatment of control to the disease is delayed and the patch remains until summer. It is known that the disease drastically progresses by the mixing infection with some kinds of Pythium fungi.
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Fungal disease occurring a lot in the warm regions and causing plant blight. The leaf at first become water-soaked and ash green and then softens like pouring boiled water. Large lesions are formed in the leaf. The infected grass withers forming patches and the grassland gradually becomes bare land. The causal organism is not yet identified. |
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Fungal disease which produces small patches mainly at early spring. The symptom is at first only indistinct patches, but they become grayish white, oval, distinct ones of about 10-20cm in diameter. The disease is called as "elephant's footprint" according to the shape of its oval lesions. The causal organism is a binucleate Rhizoctonia. It prefers comparatively low temperatures for growth.
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It occurs in the early spring and autumn. The symptom is at first white spot or stripe appearing in the leaf. Then the width of the leaf become narrow because the leaf rolls from the leaf rim. The entire plant turns to yellow, shrinks in some extent, and becomes weak, and other disease are likely occur easily. A kind of eriophyd mite (Aceria zoysiae) is always found on the infected leaf. Since virus particles are not found in the plant tissue, the disease possibly occurs only by the harm of this mite.
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