Journal of Japanese Society of Turfgrass Science

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Diseases of complex etiology have been found on golfgreens of manila grass (Zoysia matrella) during spring season in the southern part of Japan. One determinant of the diseases is identified to be binucleate Rhizoctonia and effective chemigal control measure has been established using fungicides specific for Rhizoctonia spp.. It has also been known that some other determinants might be involved because, in some cases, the disease can not be controlled by the above chemicals. The present study was undertaken to elucidate the determinants of such disease. The results obtained are summarized as follows:
(1) Pythium graminicola, P. torulosum and P. vanterpoolii were isolated in early spring. Fusarium spp. were also isolated frequently in late fall.
(2) Inoculation tests using seedlings of Zoysia japonica revealed that fungal species pathogenic at 10°C and 15°C were identified as Fusarium roseum LK, f. sp. cerealis‘Acuminatum’ and as F. nivale. Both Pythium graminicola and P. vanterpoolii were also highly pathogenic at 15°C.
(3) Combined application of benomyl (BE) in fall with metalaxy-hydoroxyisoxazole mixture (MH) in the following spring was remarkably effective to prevent symptom development on Zoysia turf in the fields. Application of MH alone in both seasons was less effective. Application of BE in fall was occasionally effective.
We conclude from the above findings that the disease is complex etiologically and manila grass is infected with F. roseum LK. f. sp. cerealis‘Acuminatum’ and F. nivale in fall and with P. graminicola and P. vanterpoolii in the following spring.

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This study deals with acquired resistance to metalaxyl of Pythium vanterpoolii causing two diseases of zoysia grass in different golf course greens and stability of the resistance.
(1) Metalaxyl-sensitive isolates were obtained from golf course greens having no application history of the fungicide before resistance had been developed.
(2) Metalaxyl-resistant isolates were found in the golf course greens after 3 years of use of the fungicide.
(3) Metalaxyl-sensitive isolates were obtamed from different other golf course greens having no application history of the fungicide.
(4) All the above-mentioned metalaxyl-sensitive golf-course-green isolates lost their sensitivity during 14-15 transfers on cornmeal agar amended with sublethal concentrations of the fungicide.
(5) All metalaxyl-resistant golf-course-green isolates retained their sensitivity during 59 transfers on cornmeal agar.

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Experiments were undertaken to determine the effect of vinegar on the control of turfgrass diseases. The growth of each isolate of four pathogenic fungi (Pythium aphanidermatum, Rhizoctonia solani, Fusarium roseum, Helminthosporium sp.) cultured in test tubes were inhibited by the addition of vinegar in the range of 0.005-0.1% acetic acid concentration.
Foliar application of vinegar diluent to perennial ryegrass (Lolium perenne) grown in plastic pot brought to enhancement of root elongation.
Similarly, such the promotion effects for plant growth were also recognized on South Japanese lawngrass (Zoysia matrelia) in the golf links.
Moreover, the occurrence of Rhizoctonia large patch and Leaf burn were restricted, and turfgrass was kept green by the foliar application of vinegar diluent.
From the experiments, utilization of vinegar was considered to be beneficial to green maintenance in golf links.

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