- 著者
- Kandai Yoshida Shunsuke Asano Yuka Sumikawa
- 出版者
- The Kansai Plant Protection Society
- 雑誌
- 関西病虫害研究会報 (ISSN:03871002)
- 巻号頁・発行日
- vol.61, pp.79-84, 2019-05-31 (Released:2019-09-01)
- 参考文献数
- 11
In 2017, chrysanthemum downy mildew, which has not been reported in Japan since 1980, severely affected chrysanthemum production in Nara Prefecture, Japan. We investigated the occurrence of the disease at the fields in Nara Prefecture and the control efficacy of thermotherapy and fungicides against it. In the field survey, over 95 % of plants were diseased in seven cultivars, while no plants with the symptoms were observed in the other six cultivars. This suggests that some chrysanthemum cultivars had resistance to downy mildew. Chrysanthemum cuttings were treated with thermotherapy (treatment with hot water and hot air). The disease prevalence in both treatments was significantly lower than that in the non-treated. Severely diseased plants were sprayed with three fungicides (azoxystrobin, manzeb, and tolfenpyrad). While azoxystrobin and manzeb reduced the disease severity compared with non-treated, its efficacy was not so high. We concluded that the use of resistant cultivars and the application of thermotherapy can effectively control chrysanthemum downy mildew.
- 著者
- Shunsuke Asano Yoshihiko Hirayama Isao Takenaka Terufumi Naka
- 出版者
- The Kansai Plant Protection Society
- 雑誌
- 関西病虫害研究会報 (ISSN:03871002)
- 巻号頁・発行日
- vol.61, pp.69-74, 2019-05-31 (Released:2019-09-01)
- 参考文献数
- 21
Spotted wilt disease caused by Tomato spotted wilt virus (TSWV) is one of the most important diseases affecting the production of bulbs and cut flowers of Dahlia variabilis in Japan. In Nara Prefecture, the main vector species of TSWV were thrips Frankliniella intonsa and Frankliniella occidentalis. The number of F. intonsa and F. occidentalis captured using blue sticky traps increased in late June and mid-May, and peaked in early July and late May to early June, respectively. TSWV viruliferous F. intonsa and F. occidentalis occurred throughout almost the entire production period in bulb production fields. TSWV might be transmitted by thrips, and the infection rates in dahlias reached up to 80% in a cut flower field. However, the use of insect proof nets greatly decreased the infection rates. In addition, the removal of dahlias with TSWV symptoms effectively decreased the rates of diseased plants. To prevent the spread of TSWV, it is important to prevent invasion of thrips using physical barriers. In addition, removal of the source of infection is an effective way to reduce the occurrence of disease.