I.R. Choi, International Rice Research Institute, Los Baños, Philippines
News in Yomiuri Online reported that in Kumamoto Prefecture, Kyushu rice plants infected with the virus disease, Southern Rice Black Streaked Dwarf Virus (SRBSDV) transmitted by the white back planthopper (WBPH), were found. Click here for the news and click “Translate” for English version. Or read the translation at the end of this post.
First discovered in Guangdong province in China in 2001 and was described by Zhou et al (2008) and Zhang et al (2008), the disease is transmitted by the white back planthopper (WBPH). The disease has been spreading in most parts of China (Read: Virus spread in China) and Northern Vietnam (Read: New virus in Vietnam). Typically infected plants have abnormal panicles, produce no yields and are dwarfed with stiff leaves or branching in the stem nodes. Small waxy swellings or galls are also commonly found on the stems.
It is likely that the virus has been carried by WBPH that migrate with the winds from China to Japan. The infected area in Kyushu is small at the moment and it is difficult to forecast its spread within Japan. More research and monitoring of the new virus will be needed to determine its potential threat.
In January 2010, the China-IRRI-Vietnam consortium was established to focus on the disease problem. In China the Ministry of Science and Technology awarded a “973” project for planthopper research and one component is for development of virus management strategies and the Vietnamese government in June 2010 has provided new funds for research (Read: Vietnam funds virus research).
“On September 16, 2010, Kumamoto Prefecture of Japan announced that they confirmed the occurrence of Southern rice black-streaked dwarf virus (SRBSDV, tentative name) disease in rice fields in the prefecture. This is the first report for the disease in Japan, although the damage is still limited, and is not expected to spread further in this year.
According the prefecture officials, the appearance of rice plants of usual shapes was reported by a rice farmer in the prefecture in late August. The plants were showing symptoms similar to those caused by rice black-streaked dwarf virus (RBSDV). However, a nucleic acid-based diagnostic test revealed the disease was actually caused by SRBSDV, not RBSDV, which was discovered in Southern China in 2001. The SRBSDV disease is currently prevalent in Northern Vietnam and Southern China.
The SRBSDV disease was observed across the entire prefecture, although the sizes of damaged areas in the individual rice fields were less than one meter in diameter at most. The disease is known to be transmitted by white backed plant hopper. The disease is not expected to spread further this year since WBPH is not able to overwinter in Japan, and the peak of vector migration is nearly over this year.”