抄録
Significant and sometimes devastating effects of agricultural exterminators on vegetation have long been recognized. Our purpose of this study is to present information of the effects of agricultural exterminators scattered in the field. Observation was carried out at Amagi Plain in Fukuoka Prefecture. Mulberry branches with leaves were set at network points. We scattered the fluorescent particles (F.P.) and agricultural exterminators simultaneously from a continuous point and a line source. We fed mulberry leaves to silkworms and examined the influence of agricultural exterminators on silkworms.
From the comparison of observed F.P. concentrations and degrees of injured silkworms with calculated concentrations by the diffusion equation for a finite line source, the following results are obtained:
1) The degrees of injured silkworms are in fair agreement with the concentration values calculated by a formula of the normal distribution type.
2) As for the damage of silkworms fed on the mulberry leaves contaminated with agricultural exterminators (cartap), much damage will occur for the accumulated concentration exceeding 1.06×10-1g/m2, medium damage for 4.17×10-2-1.06×10-1g/m2 and little damage for 1.22×10-3-4.17×10-2g/m2.
3) The damage of silkworms is very slight when they are fed on leaves set at the leeward of structures and bushes. It suggests an effect of vital significance by topography and roughness on the diffusion near the ground.
4) Before scattering agricultural exterminators, special care must be taken to wind speed, wind direction and atmospheric stability.
