Abstract
The experiments were conducted to clarify the influence of transplanting date on the occurrence of rice virus in field condition of 1984. The rate of RBSDV (rice black-slreaked dwarf virus) viruliferous vector, smaller brown planthopper (Laodelphax striatellus Fallen), was shown to be $13.6\%$ at the 2nd adult and that of rice stripe virus (RSV) viruliferous was $6.7\%$ at the 2nd adult. The vector in the field was begun to come from May 29, the maximum densities were 19.6 insects per hill on June 13 in cultivar Chucheongbyeo, 19.3 in Nagdongbyeo, 7.4 in Cheongcheongbyeo and 4.9 in Samgangoyes. The number of vectors per hill was inclined to increase by early transplanting. Although the infection of rice virus in nursery bed was not recognized until May 30 transplanting, the nursery infection could be seen from June 10 transplanting. The highest rate of nursery infection with RSV was $4.1\%$ at June 10 transplanting plot, and that of RBSDV was $14.2\%$at June 20 trans planting plot. The infection of rice virus in paddy field was the highest at May 20 transplanting plot, the lowest at July 10 plot. The earlier transplanting, the more severe occurrence of rice viruses. Occurrence of infected plants with RBSDV was shown to increase more rapidly at May 20 and May 30 planting plot than May 10 plots. However, the occurrence of infected plant with RSV was more rapid at May 10 transplanting plot than May 20 and 30.
밀양 지역의 애멸구 2회 성충의 바이러스 보독충율은 검은줄무늬오갈병이 $13.6\%$, 줄무늬잎마름병이 $6.7\%$이었다. 본 논에서 애멸구 2회 성충은 5월 29일부터 나타나기 시작하여 6월 13일에 최성기였는데, 이때의 주당애멸구 서식수는 추청벼, 낙동벼가 19.6, 19.3마리로 높았으나 삼강벼, 청청벼는 4.9 및 7.4마리로 비교적 낮았고, 이앙 바로 뒤의 벌레수는 극히 적었으며 이앙이 빠를수록 벌레수가 많은 경향이었다. 바이러스의 못자리감염은 5월 30일까지는 인정되지 않았으나, 그 후부터 감염이 인정되었는데 6월 20일 이앙구는 검은줄무늬오갈병의 못자리감염율이 가장 높은 경향이었다. 바이러스 본논감염율은 이앙이 빠를수록 높은 경향이었으며 그 가운데서도 5월 20일 이앙이 가장 높았고 7월 10일 이앙이 가장 낮았다. 검은줄무늬오갈병은 5월 10일 이앙이 5월 20일과 5월 30일 이앙에 비하여 발병증가가 완만하였으나, 줄무늬잎마름병은 5월 10일 이앙이 발병증가가 빠른 경향이었다.