Studies on the Rhizoctonia Large Patch of Zoysia turfgrass (IV)

Vicissitude of number of the fungi isolated from this disease after treating with the fungicides

Abstract

1. This report was carried out to investigate the Vicissitude of number of the fungi isolated from Rhizoctonia Large Patch after treating with the fungicides, and, to experiment the relationship between the permiability of the fungicides, the volume of diluted solution and the spreader, and, the differeuce of the fungicidal effect with the same volume of diluted solution on the different managementing turf.
2. After each fungicide was treated with the customary diluted solution on the lesion in autumn, the fungi were isolated at intervals from the part of leaf and stem (the clipping surface to the depth of 1.5cm) untill spring.
So that, the number of the fungi, which each fungicide was treated on, decreased extremely at the day, but not disappeared. After the decreasing situation was continued in a definite period of time, the number of the fungi increased again.
The period of the decreasing situation of tolclofosmethyl was continued above 16 weeks, and, TPN, mepronil and iprodione were contin ued from 4 to 8 weeks.
In case of the treatment with each fungicide at 2 times of the customary volume, the number of the fungi of tolclofosmethyl, TPN and mepronil decreased more than tho customary volume at the day.
The period of the decreasing situation was continued longer than the customary volume among the fungicides. And the fungi dis appeared among the fungicides. After that, the fungi increased again as the same number as the custimary volume.
But the number of the fungi and the period of decreasing si tuation with iprodione were the same as the customary volume.
After each fungicide was treated on the disease, the effect appeared at 3 hour later.
3. In order to see the vicissitude of number of the fungi in the runner (the depth of 1.5 to 3.5cm), the fungi were investigated after the customary diluted solution of tolclofosmethyl at 1 time and TPN at 2 times in intervals of 2 weeks were treated respectively.
So that, the fungi were isolated from the plot of each fungicide as the same number as the plot of no-treatment in all nerind.
4. In order to see the permiability of the fungicides, the fungi were isolated from the runner and the root (the depth of 3.5 to 5.5cm) after a certain volume of the customary diluted solution of tolclofosmethyl and TPN was treated.
So that, the fungi with 8 times of the customary volume of each fungicide were the same number as half of no-treatment in the runner.
The fungi in the root disappeared with 4 times of tolclofosmethyl and 8 times of TPN respectively.
To compare the permiability, the solution of tolclofosmethyl, which the osmotic and the customary spreader were added to, was treated on the leision.
So that, the fungi in runner, which were isolated from the plot of the osmotic and the cust omary spreader respectively, were the same number.
5. After the equal volume of the solution of tolclofosmethyl was treated on the lesion of green and fair-way respectively, the fungi were isolated from the part of the runner.
So that, the number of the fungi on fair-way was more than on green at 2 times of the customary volume.
And the treatment with 2 times (2g/2l/m²) of the customary volume of the solution was more effective than with 2 times (2g/l/m²) of only the dosage.