Abstract
This study was carried out to establish rational methodologies for the use of pesticide formulations to be sprayed after water-dilution. Hardness and electric conductivity of six major river water and ground water sampled from 52 sites in major rice-growing areas across the country ranged from 5 to 324 ppm(av. 90 ppm) and from 0.038 to 1.078 dS/m(av. 0.265 dS/m), respectively, which are acceptable for diluent water of pesticides. The pH changes in pesticide spray solutions with time after preparation mainly depended on the pH of the water used for pesticide dilution. The surface tensions of pesticide spray solutions reduced slightly with time after preparation, irrespective of kinds of pesticide formulations. Suspensibility of WPs became worse with an increase in the hardness and salt concentrations of diluent water, even though the degree was negligible. Emulsion stability of ECs became worse with an increase in hardness and salt concentrations of diluent water. Degradation rates of the active ingredients of pesticide spray solutions 3 days after preparation were less than 5%, regardless of mixing or non-mixing of two or more pesticides. Consequently, the spray solutions of most pesticides were usable until two to three days after preparation unless physical properties deteriorated. The tank-mixing order of EC and WP formulations did not make any differences in all the physical properties of pesticide spray solutions. However, the proper order for the tank-mixing of compatible pesticides was WP, WG, SC, EC, and SL, because the order is easy to prepare the pesticide spray solutions. The efficacy of pesticide spray solutions on the respective target pathogens and insect pests of rice plants three days after preparation was recorded over 95% of that of 0 day, which was almost the same as that of the solutions applied punctually after preparation.
환경오염을 최소화하고 병해충 방제효과를 증진시킬 수 있는 희석제농약의 적정사용기술을 확립하기 위하여, 희석용수의 수질이 살포액의 물리성과 약효에 미치는 영향 등을 검토한 결과, 국내 6대강의 하천수와 52지점의 지하수에 대한 경도는 $5{\sim}324$(평균 90) ppm, 전기전도도는 $0.038{\sim}l.078$(평균 0.265) dS/m의 범위로 전반적으로 농약의 희석용수로 양호한 수준이었다. 농약살포액의 pH는 주로 희석용수의 pH 변화에 좌우되었으며, 표면장력은 시간이 지날수록 낮아져 부착면에서는 유리할 것으로 판단되었다. 희석제농약의 유화성, 현수성 등의 물리성은 용수의 경도, 염농도의 영향을 받는 것으로 나타났으며, 농약주성분의 경시적 분해율도 조제 3일 후 대부분 5% 이내로 안정하였다. 유제와 수화제 농약의 혼용순서에 의한 살포액의 물리성은 수화시간을 제외한 모든 면에서 동일하였으며, 단지 수화제(WP>WG>SC)>유제>액제 순으로 희석하는 것이 살포액의 조제작업 측면에서 보다 용이하였다. 조제 3일 후 농약살포액의 각각의 적용병해충에 대한 방제효과는 조제 당일에 비해 95% 이상의 높은 방제효과를 유지하였다.
