殺菌劑對梨赤星病感染源之抑制效果評估

Evaluation of inhibitory effect of fungicides on pear rust inocula

梨赤星病普遍發生在梨樹與龍柏共存的區域，除施用農藥在梨樹上及減少龍柏數量之外，近年來臺灣中部地區防治梨赤星病的替代策略還有噴施殺菌劑在龍柏植株上。本研究目的為在實驗室階段評估殺菌劑對龍柏上的梨赤星病感染源（冬孢子及擔孢子）作用的效力。六株用於實驗的梨赤星病菌株依形態與核醣體大次單元序列特徵鑑定為Gymnosporangium asiaticum。受測試的9種殺菌劑當中，波爾多液與三氟敏在推薦劑量及不同測試濃度顯著抑制冬孢子發芽，三氟敏在83μg a.i./ml可完全抑制冬孢子及擔孢子發芽，施用此濃度的三氟敏於龍柏上的梨赤星病感染源有潛力降低梨樹受梨赤星病危害。

"Pear rust is a prevalent plant disease in regions where pear trees and junipers (Juniperus chinensis) coexist. Additional to pesticide application on pear trees and reduction the number of junipers, spray of pesticides on junipers has recently become an alternative strategy to manage the disease in central Taiwan. Objective of this study is in vitro evaluation of efficacy of fungicides on pear rust inocula, including teliospores and basidiospores produced on junipers. Six pear rust samples used in experiments were identified as Gymnosporangium asiaticum via the morphology and the 28S large-subunit (LSU) rDNA sequences. Among 9 fungicides tested, Bordeaux mixture and trifloxystrobin inhibited teliospore germination significantly at recommended dosages and at various concentrations. Trifloxystrobin completely stopped germination of teliospores and basidiospores at 83 μg a.i./ml. Application of trifloxystrobin at the dosage to the inocula on junipers has potential to suppress development of the pear rust disease."