Investigation on the turfgrass diseases through the requests of golf-courses during the past three years

Abstract

1. This report is the result of investigation on the turfgrass diseases which broke out in golf-courses throughout the nation from May, 1978 to July, 1981 but failed to be fully researched. This report deals especially on those undiagnosed diseases.
2. The number of investigation on the diseases was 21, 24, 13 and 12 from the year 1978 to 1981 respectively.
3. Speaking of weather, it was dry in the summer of 1979, while 1980 had a very cool summer. In the year of the dry season, there were greater cases and kinds of diseases which were difficult to diagnose while in the year of the cool summer there were fewer.
4. In regard to the kinds of diseases, there was the greatest number of Leaf spot followed by Shizumi-sho (Zoysia disease whose fungus is unknown but which shows the symptom of curclic sunk Zoysia turfgrass), Zoysia Large patch (Rhizoctonia solani Kühn), Bentgrass Brown patch, Bentgrass Grease spot, Zoysia Fairy rings and Zoysia Spring dead spot.
Also discovered were brand-new diseases and there were another cases which were mistakenly thought to have been caused by fungi.
5. In most cases, the fungus which is the primary cause of the disease was rarely separated singly but with a few other fungi simul taneously.
Especially evident was the case of Helminthosporium (Curvularia) which was separated in most diseases. Fusarium, Pythium and Rhizoctonia were also rather frequeutly separated.
On the other hand, in some diseases, which seemingly appeared to be caused by the fungus, the fungus of the primary cause could not be found.
6. Judging from separated fungi, it was difficult to diagnosed the diseases such as Leaf spot, Shizumi-sho, Zoysia Large patch and so on.
Among them, Zoysia Leaf spot showed similar symptom as Zoysia Large patch and Zoysia Foot rot.
However, Zoysia Leaf spot, which showed the same symptom and was suspected of being Zoysia Large patch, was not Zoysia Large patch. While the fungi of Rhizoctonia and others along with Helminthosporium (Curvularia) were separated from this Zoysia Leaf spot, the strain of Rhizoctonia was different from the one seen in Zoysia Laige patch.
From Zoysia Leaf spot which showed the same symptom as Zoysia Foot rot, Pythium was rather frequently separated.
On the other hand, even among those easilydiagnosed diseases such as Bentgrass Brown patch or Bentgrass Grease spot, there were cases that the other fungus along with the one of the primary cause was detected or that the fungus of the primary cause was missing.
Also found was that Bentgrass Grease spot could break out in spring.
7. As for new diseases, Yellowish brown patch, caused by Rhizoctonia solani, was detected on the Bentgrass under temperatures of 10°C from late autumn to early spring.
Also detected was the disease, showing the same symptom as Bentgrass Grease spot, which broke out on Zoysia turfgrass during the summer season. From this disease, Pythium spp. was separated.