|Title:||Control of Peronophythora fruit downy blight of lychee by neutralized phosphorous acid||Other Titles:||利用中和後之亞磷酸防治荔枝果實露疫病||Authors:||Pao-Jen Ann
|Keywords:||Lychee;Litchi chinensis;Lychee fruit downy blight;Peronophythora litchii;Disease control;Phosphorous acid;Induced resistance;荔枝果實露疫病;Peronophythora litchi;病害防治;亞磷酸;誘導抗病||Issue Date:||Dec-2011||Publisher:||中華民國植物病理學會||Journal Volume:||20||Journal Issue:||3-4||Start page/Pages:||90-97||Source:||植物病理學會刊||Abstract:||
Field studies were conducted to evaluate the effect of neutralized phosphorous asid solution (NPA) on the control of fruit downy blight of lychee (Litchi chinensis) caused by Peronophythora litchi during 1999-2003. Trees of lychee, variety ‘Black Leaf’, were sprayed with NPA at 1000 mg/L, 2 or 3 times at 7-day intervals, at the fruit maturing stage and then inoculated with sporangial suspension of P. litchi at 200-500 spores/mL. Matured fruits were harvested and percentage of downy blight fruit was recorded. Results of the 3-year field trials showed that lychee trees sprayed with NPA significantly (P<0.01) reduced the incidence of fruit downy blight (0.5-11.8%), compared to untreated controls (26.1-46.6%). The treatment of NPA also was as effective as the treatment of mancozeb 80WP (dilution 500 times), a commercial synthetic chemical registered for the control of lychee fruit downy blight in Taiwan. Meanwhile, three applications of NPA in the fields not noly significantly (P<0.01) reduced the incidence of postharvest Peronophythora fruit rot of lychee (0-16%), compared to the untreated control (12.2-96.6%), but also delayed the development of postharvest fruit downy blight by 2-4 days. However, treatment of freshly harvested lychee plants at fruit development or maturing stage in the fields to induce resistance of lychee fruits against P. litchi and thereby, reduce downy blinght of lychee fruits in the field and at postharvest stage.
近年來，農試所研發一種簡單的方法配製亞磷酸中和液(NPA)，將等重量之氫氧化鉀加入亞磷酸水溶液中和後使用。於 1999 -2003 在田間施用NPA，以評估其對荔枝果實露疫病的防治效。在黑葉近成熟期，每隔7天噴布濃度1000 mg/L之 NPA一次，共2-3次，相隔7天之後，再接種露疫病菌孢囊懸浮液（濃度為200 -500 spores/mL）。結果顯示，NPA在田間防治荔枝果實露疫病之效非常好，果實發率可從26.1 -46.6% 下降為0.5 -11.8%。同時， NPA防治果實露疫病的效與噴施三次 80%鋅錳乃浦可濕性粉劑（稀釋 500 倍）的效果一樣好，無顯著性差異。此外人工接種之結果顯示，在田間施用相同濃度的NPA 2-3次，同樣可以顯著降低採收後果實露疫病之發率，從12.2-96.6% 下降至 0-16% ；還可以延緩果實露疫病徵之出現達 2-4日。然而，以相同濃度之NPA處理採收後的果實再接種露疫菌，則無法顯著降低果實之發病率，此項結果顯示NPA必須施用於田間才有防治荔枝果實露疫病之功效。
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