Abstract
The relation between uniformity of distribution and herbicidal effect of fine-granular herbicides and the performance of the blow head of applicator newly devised for fine-granules were investigated.
1) Herbicidal effect of fine-granule formulation of benthiocarb-prometryne mixture was examined at various rates 0 to 300 per cent of the standard rate (5kg/10a). When the herbicide was applied uniformly at rates more than 80 per cent of the standard, weeds were reduced to less than 2 per cent of the untreated plots.
2) On applying the fine-granular herbicide on upland fields at the standard rate, the desired range of variation in distribution, though it is more or less dependent on weed species and herbicides, was considered to be practically less than ±20 per cent of the standard.
3) To apply the fine-granular herbicide with the newly devised blow head tied with the commercial granule-applicator, it took 5 minutes per 10 are at the driving speed 0.7m/sec, with 5m spreading swath width. Uniformity of distribution expressed in terms of the coefficient of variation was 17.3 to 31.0 per cent in applying fine-granular herbicide at the rates 0.5 to 4kg/10a, and 20 per cent in applying granular herbicides formulated for lowland fields at 3kg/10a.
