Fungicidal effects of two fumigants on Phellinus noxius in the soil

• Published in: 樹木医学研究 Vol. 26; no. 4; pp. 189 - 195
• Main Authors: Sakai Yasuko, Itoh Shunsuke, Akiba Mitsuteru, Ota Yuko, Sahashi Norio
• Format: Journal Article
• Language: Japanese
• Published: 樹木医学会 31.10.2022; Tree Health Research Society, Japan
• Subjects: Brown root rot; chemical control; Phellinus noxius; シマサルノコシカケ; 南根腐病; 薬剤防除
• ISSN: 1344-0268; 2189-7204
• DOI: 10.18938/treeforesthealth.26.4_189

Brown root rot caused by Phellinus noxius is a serious plant disease, and has been causing serious problem in tropical and subtropical regions. At present, the only effective control procedure is entirely removing infected trees and the surrounding soil. However, these measures are labor-intensive and time-consuming, therefore practical alternatives is necessary. We evaluated the effects of two fumigants chloropicrin and dazomet on P. noxius. Branches artificially inoculated with P. noxius were buried in soil and subsequently fumigated. After fumigation, the branches were collected and examined for the presence of P. noxius. No P. noxius was isolated from branches retrieved from chloropicrin-treated soil, whereas the isolation rate of P. noxius from dazomet-treated was significantly lower than the control. In addition, to confirm the workability and safe practical use of chloropicrin, we established a test plot (6.5 m×12 m). The treatment took 7 hours by 5 workers. During the test period, no gas leakage was detected outside the covering sheet. In addition, any gas was not detected inside the sheet, 11 days after fumigation treatment. We accordingly confirmed that chemical fumigation with chloropicrin and gas barrier film could be safely applied for control of P. noxius even at practical scale. 南根腐病はシマサルノコシカケ（Phellinus noxius）が引き起こす樹木病害で，熱帯・亜熱帯地域で深刻な問題となっている．本病による被害が発生した場合，罹病木とその根等の残渣を含む土壌を撤去する以外に防除方法はなく，低コストで簡便な防除法の開発が望まれている．そこで，クロルピクリンとダゾメットの2つの土壌くん蒸剤が本菌に与える影響について調査した．シマサルノコシカケ（南根腐病菌）を蔓延させた3樹種の枝を土壌中に埋め込み，くん蒸処理後に掘り出して菌を組織分離したところ，クロルピクリン処理区では本菌は分離されず，ダゾメット処理区では無処理区に比べて分離率が有意に低かった．さらに，施工時の作業性と安全性を確認するために，公園内の緑地でクロルピクリンと被覆資材としてガスバリア性フィルムを用いた土壌くん蒸処理を行ったところ，試験地（6.5 m×12 m）のくん蒸作業には5人の作業員で7時間を要した．また，くん蒸作業終了後から試験期間を通してフィルムの外側にクロルピクリンガスの漏出は認められず，処理11日後には土壌中およびフィルム内の空気からもガスは検出されなかった．ガスバリア性フィルムを使用して用法を正しく実施することで，事業規模でもガスの漏出なくクロルピクリンによる土壌くん蒸処理を行うことができることが分かった．