Weed control using apple snails in paddy fields

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K05544
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 39020:Crop production science-related
• Research Institution: Tokai University
• Principal Investigator: Abe Jun 東海大学, 農学部, 教授 (60221727)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: スクミリンゴガイ / イネ / 育苗 / 雑草 / けい酸施肥

Outline of Final Research Achievements

In Kumamoto Prefecture, weeding is done with alien invasive species apple snails, mainly by natural farming farmers. But even in such paddy fields, the rice is also often damaged by apple snails, causing a decrease in yield.
To reduce feeding damage caused by apple snails, (1) transplant medium or adult seedlings rather than young seedlings, (2) use varieties that are less likely to be damaged by feeding such as Nikomaru, and (3) use an appropriate amount of nitrogen fertilizer when raising seedlings. (4) apply silicic acid materials during seedling raising. The use of silicic acid materials was thought to be particularly effective in hardening rice seedlings and reducing feeding damage after transplanting.
In addition, by maintaining soil hardness without tilling after harvesting, it is possible to reduce the number of apple snails that overwinter in the paddy soil.

Free Research Field

作物学

Academic Significance and Societal Importance of the Research Achievements

外来生物であるスクミリンゴガイは拡散を防ぐことが望ましいが，既に侵入してしまった地域においては，その存在を前提とした稲作の技術を確立する必要がある．熊本県では，スクミリンゴガイが侵入した地域で，雑草の実生をスクミリンゴガイに食べさせることで除草剤の使用を軽減している農家が少なくない．ただし，イネも食害を受けるために株数や，茎数・穂数が減る被害が出やすく，代かきによる土壌表面の均平度などが問題となる．
本研究では，イネ育苗時のけい酸資材の利用など，安価で簡便な技術により，スクミリンゴガイによるイネ食害の軽減が図れることを明らかにしており，水稲作の現場において役立つ知見を提供できた．