To attenuate and control the spread of infectious disease, a body of research has been conducted to generate safe vaccines and to continue national-level surveillance. However, understanding on viability and persistence of avian influenza virus (AIV) in infected carcasses, and effective disposal approaches are still limited up to date. Here, using HA test and RT-PCR, we assessed active status of AIV and degradation of viral RNA in collected specimens at different sites and time points. First, AIV infectivity was recovered until day 2, and viral nucleic acids persisted to day 14 and 21 in inorganic and organic samples, respectively, in sealed vials incubated at room temperature. Second, AIV was totally inactivated in all examined specimens, and viral RNA was not detectable at all time points tested at least one month post-infection in AIV-inoculated carcasses buried directly in soil or fiber reinforced plastic (FRP) bin. Lastly, among different burial sites in South Korea, 6 out of 17 sampling sites in Jeonbuk province showed the presence of viral genetic materials, while the rest of the field samples displayed neither the presence of infective AIV nor detectable viral RNA. This study showed a linear relation between time and degradation degree of viral RNA in buried samples suggesting that burial disposal method is effective for the control or at least attenuation of spread of AI infection in infected animals although consistent monitoring is required to verify safety of disposal.
Background : Ginseng root rot caused by soil-borne pathogens, Cylindrocarpon destructans and Fusarium solani, is a major factors of replanting failure in ginseng cultivation. Some of the phenolic compounds detected in the soil of commercially cultivated American ginseng could inhibit the seed germination and seedling growth of American ginseng. Our study is to investigate the causes of replanting failure of ginseng by overhead flooding treatment and soil incorporation of ginseng fine root in soil infected with root rot pathogens. Methods and Results : To make soil occurring continuous cropping injury, 2-year-old ginseng infected with Cylindrocarpon destructans replanted in soil cultivated ginseng for 5 years. Treatment are as follows: 1) control, 2) water of 2ℓ was irrigate infected soil of 20ℓ, 3) ginseng fine root of 20g was mixed with infected soil of 20ℓ. Soil pH was increased, while other inorganic components were significantly reduced by overhead flooding treatment. Soil incorporation of ginseng fine root decreased soil pH, but increased EC, NO3, P2O5 and K, meanwhile, did not affected changes in organic matter, calcium, magnesium, sodium. Irrigation treatment in soil occurring replanted failure promoted distinctly above-ground growth of ginseng, and inhibited the occurrence of root rot because inorganic nutrient like NO3, P2O5 and K were decreased to optimal levels, and the density of soil pathogens could be reduced. Growth of ginseng was not inhibited, while root rot was promoted by soil incorporation of ginseng fine root. Conclusion : Irrigation treatment was effective in promoting the growth of ginseng and inhibited root rot distinctly. Ginseng fine root remaining in the soil after ginseng harvest did not affect the above-ground growth of ginseng, while promoted the occurrence of root rot.
Barley Yellow Mosaic Virus (BaYMV) caused significant reduction in barley yield and is difficult to control due to alive parasitic soil-borne fungus, Palmyra gamines that transmits the, virus. Previous studies have indicated that a virus-free soil could be infested by using virus-contaminated farming machineneries and implements. For the further confirmation of this finding, different proportions of BaYMV-infested soil were mixed into virus free soil. Three barley varieties (Hordum vulgarae, cv "Olbori", "Baegdong" and "Sacheon 6") were sown in pots treated with different rate of P. graminis-infested soil ranging from 0% to 100% in October 20, 2001. Results showed that BaYMV infection increased as the rate of infested soil increased. Initial symptoms were observed in a pots treated with 10% infested soil in all the 3 varieties of barley. "Olbori" had about 5% infection in 20% infested soil and about 10% infection in 40% or 50% infested soil and about 20% infection in 60% infested soil. In "Baegdong", the trend of BYMV occurrence was similar with "Olbori" but the time of severe infection was earlier than "Olbori". BaYMV infection in "Sacheon 6" was even earlier than "Baegdong" with much more severe symptoms than "Baegdong". The growth rate of barley was affected by about 19-22% when grown in 20% infested soil. As the rate of BaYMV infested soil increased the heading date was delayed but the maturing date was early in "Olbori" and "Sacheon 6". Also, reduction rate of culm length in 3 varieties increased with increase of infested soil content. However, "Olbori" showed the highest reduction. "Sacheon 6", have been characterized with long spike length, however was significantly reduced as the infested soil increased. On the other hand, spike length of "Olbori" was not significantly affected despite of increased of infested soil. The reduction rate of 1000 kernel weight was higher in large kernel size cultivar "Sacheon 6" and "Olbori" than small kernel size "Baegdong" as increase of BaYMV-infested soil content.
1999년부터 2001년까지 전국42개 지역에서 토양전염성 맥류바이러스를 조사한 결과 강원도 영월, 전라북도 무주, 충청남도 공주, 보령, 서천 포장을 제외한 37개 포장에서 BaYMV, BaMMV 및 SbWMV가 발생하고 있었다. 또한 토양전염성 맥류바이러스 상습 발병지 10개 장소에 겉보리 10품종, 쌀보리 16품종, 맥주보리 6품종, 밀 2품종을 파종하고 저항성 조사를 실시한 결과 겉보리는 조강보리, 쌀보리는 내한쌀보리 및 논산과1-6품종이 비교적 여러지역에서 저항성 높은 품종으로 나타났다. 그리고 일본에서 분양 받은 15품종도 대부분이병성으로 나타났으나 특이하게 익산, 영광 및 예산지역에서 저항성 품종이 많았다. 지역간 품종에 따른 바이러스 혼합 감염을 조사한 결과 조사 10개 지역 모두 BaYMV, 및 BaMMV가 혼합 감염되어 있었고, BbWMV는 예산, 진주, 나주 및 익산지역에 혼합감염되어 있었다. 그러나 영광지역에서는 사천6호 품종을 제외하곤 BaYMV만이 발생하였다. 일본 분양 품종은 예산에서만 BaYMV가 감염되었고 나머지 지역에서 모두 BaMMV 및 BaYMV에 혼합 감염되 어 있었다.