1981 Volume 10 Issue 2 Pages 121-128
1. This experiment was carried out by artificial inoculation to see under what field conditions the outbreak of Rhizoctonia Large patch in the Zoysia turfgrass lawn was most probable. Also examined was the influence of green keeping operations on the outbreak of this disease.
2. When the amount of the 100g/m2 soil and wheat bran mixed with the culture of Rhizoctonia solani was inoculated into the field of Zoysia turfgrass lawn in the spring, the outbreak of the disease was observed only in the first and the following spring season but not in autumn.
3. To test the relationship between the outbreak of the disease and the amount of the inoculant, the soil and wheat bran mixed with the culture of Rhizoctonia solani of 50, 100, 200g/m2 respectively was inoculated into the turf grass. As the result, the one least inoculated showed the highest degree of the outbreak, indicating no direct relationship between the outbreak of the disease and the amount of inoculant used.
4. In order to clarify in which season the outbreak of the disease most likely occurs, the inoculant of 200g/m2 was inoculated into the turf grass lawn once or twice a month from autumn to spring. The obvious outbreak appeared in autumn and spring. It was also observed that all the inoculations from autumn to spring resulted in the outbreak of the disease in spring.
5. When the relationship between the outbreak of the disease and the resodding was examined using the inoculant with the amount of 200g/m2, the newly layed turfgrass lawn was infected more quickly than the one without resodding because of the damage caused by the lifting and sodding.
6. To see whether or not the removal of the thatch containing the fungi would decrease the chance of the outbreak of the disease, the thatch of the turfgrass lawn, inoculated by the 50g/m2 inoculant and developed with the fungi, was removed by means of vertical mowing. The result was that the outbreak of the disease was greater in the turfgrass lawn whose thatch containing the fungi was removed than the removed-free turfgrass lawn, because of the damage made to the turfgrass by the vertical mowing.
7. When the relationship between the outbreak of the disease and the vertical mowing was examined using the vertically-mowed turfgrass inoculated by 200g/m2 inoculant, the outbreak of the disease in the vertically-mowed turfgrass was obviously greater not only in this disease season but also in the next. This was caused by the damage made to the turf-grass by the vertical mowing.
8. To see the relationship between the outbreak of the disease and the top-dressing, the following three cases were tested using the inoculant of 200g/m2 : (1) the top-dressing after the inoculation, (2) the inoculation after the top-dressing, and (3) the inoculation without the top-dressing. The result showed that the top-dressing does contribute to the outbreak of the disease, especially when the topdressing was attempted after the inoculation.
9. When the experiment was made to show the relationship between the outbreak of the disease and the cored turfgrass lawn using the 200g/m2 inoculant, the cored turfgrass lawn contributed to the some degree of the outbreak of the disease as the uncored turf-grass lawn, thus indicating no relationship between the two.
