菊花害蟲之發生與防治

Abstract

菊花主要供外銷，爭取外匯。近年來輸日切花中每因含有活蟲，致遭買方燒毀或強制燻蒸，影響切花品質和菊農之收入甚鉅。本文主要在敘述臺中區農業改良場數年來在菊花害蟲研究所得結果，並就菊農在菊花害蟲田間防治上應改進之問題加以檢討。 為害菊花害蟲之種類，經數年調查結果，計有14種。其中以蚜蟲、薊馬、葉瞞三類發生較普遍；鱗翅目類害蟲雖零星發生，但常給外銷切花帶來不少麻煩。根據棲群消長資料，顯示刺吸式口器害蟲於早季較多，長期降雨對其密度有抑制作用。但咀嚼式口器害蟲受影響較小。由於菊花栽培期不整齊，訂定防治適期不易，原則上可按各植期而定。一般而言，在幼株期（培土，架支持網前）宜防治1~2次，開花期以前再酌情防治1~2次，間隔7~10天。外銷菊花以花蕾出現至切花期最重要，應徹底防治3~5次，間隔3~5天。防治藥劑經從20餘種殺蟲劑中，篩選出對蚜蟲防治效果較優者有25.3％美文松乳劑等6種，防治薊馬類有2種，防治葉蟎有50％錫蟎丹可濕性粉劑等5種。經年連續施用多年後，部份藥劑藥效已顯著下降，似已產生抗藥性。菊花品種甚多，對不同害蟲及不同藥劑有不同的反應，就害蟲防治的觀點，宜栽種抗蟲性品種，而對藥劑比較敏感且易發生藥害者應避免栽植。並需不斷改進栽培技術，減少害蟲之發生。殘株、廢園應妥善處理，勿任意擱置而變成次期為害蟲源。加強病蟲害共同防治工作，及尋求其他治蟲新技術，期能逐一解央目前在田間防治上所遭遇之困境。 In Taiwan, chrysanthemum grown is primarily for export and has helped earn large sum of foreign exchange for the country. In recent years, destruction by fire or mandatory fumigation has often been imposed on the cut flowers exported to Japan because of the infestion by live insect pests. These actions result either in downgrading of quality of the cut flowers or serious reduction of farmers¡¦ income. This article describes some results of the work on insect pests of chrysanthemum performed in this station, and makes assessment of the control measures taken by farmers which need improvement. Surveys of several years indicate that among the more than 10 different insect pests on chrysanthemum, aphids, thrips and mites occur most frequently. Lepidopterous insect pests, though occurring only sporadically, bring much trouble. Higher populations of sucking-type insect pests are found in dry seasons due to the inhibitory action of continuous rain on population density. This suppressive action is less apparent to the chewing-type insects pests. The ununiformity of culturing period of chrysanthemum makes the effort of timing of control difficult, which generally must vary with planting time. In general, 1 to 2 sprays are necessary during early stage of the plant (before soil banking and setting up supporting nylon net). According to need, 1 to 2 sprays at an interval of 7 to 10 days can be made before blooming. The most critical stage for exporting chrysanthemum is between the budding and time of cutting. Three to 5 sprays at an interval of 3 to 5 days are absolutely necessary. Screened from more than 20 insecticides are 6 insecticides including 25.3% EC mevinphos for aphids, 2 for thrips, and 5 including 50% WP Plictran for mites. Significant reduction of afficacy of some insecticides has been noticed in the field and this may indicate development of resistance of insects due to continuous application of insecticides for many years. Because of the many varieties of chrysanthemum which react differently toward insect pests and insecticides, it is recommended, for insect pest control, that insect-resistant varieties should be preferred to those susceptible to insecticides and thus easily showing phytotoxicity symptoms. Improvement of culturing techniques may decrease the occurrence of insect pests which may have favorable effect on their control. Discarded plant parts and abandoned fields which may become the sources of infestation must be carefully taken care of. Strengthening of cooperative pest control program and searching for new control measures will eventually ensure overcoming of the difficulties encontered in the field.