Alternaria brown spot is considered the main disease of tangerines in the State of Paraiba. The objective of work was to evaluate vegetal tinctures from bitter melon (<em>Momordica charantia</em>) and guav...Alternaria brown spot is considered the main disease of tangerines in the State of Paraiba. The objective of work was to evaluate vegetal tinctures from bitter melon (<em>Momordica charantia</em>) and guava (<em>Psidium guajava</em>) leaves, as an alternative control for Alternaria brown spot in tangerine. The effects of vegetal tinctures were tested in leaves and fruits (detached) of tangerine “Dancy” inoculated with tangerine pathotype of <em>Alternaria alternata</em>. The effect of tinctures on mycelium growth and spore germination of the pathogen was tested. Tinctures at 20% concentration promoted reduction of disease severity. A reduction of 80% in the diameter of leaf lesions was observed for bitter melon tinctures and 75.3% for guava tinctures. In fruits, the reduction was 48.4% (bitter melon tinctures) and 43.3% (guava tinctures). Guava tinctures, starting at a concentration of 5%, inhibited 100% of mycelium growth of tangerine pathotype of <em>A. alternata</em>, while the use of bitter melon tinctures inhibited 100% of mycelium growth starting at a concentration of 10%. The greater sensitivity to tinctures observed when these were added to the culture medium when compared to inoculation in leaves and fruits may be explained due to the higher exposition of the pathogen to the active principle when the vegetal tinctures were added to the culture medium, than when tinctures were sprayed over the vegetal surface in fruits and leaves. The number of germinated spores decreases 76.7% and 82% when using tinctures from guava and bitter melon (20%). Tinctures from bitter melon and guava are potential tools for alternative management of the Alternaria brown spot in tangerine “Dancy”.展开更多
柑橘链格孢褐斑病(Alternaria brown spot,ABS)是新近在我国局部地区新发现的病害,主要为害宽皮柑橘及某些杂交种柑橘,引起落叶、落果和枯梢,不仅影响产量,还影响果实的销售,造成严重损失,并且病害呈逐渐扩散和加重的趋势。药剂防治是...柑橘链格孢褐斑病(Alternaria brown spot,ABS)是新近在我国局部地区新发现的病害,主要为害宽皮柑橘及某些杂交种柑橘,引起落叶、落果和枯梢,不仅影响产量,还影响果实的销售,造成严重损失,并且病害呈逐渐扩散和加重的趋势。药剂防治是目前防治ABS的最有效措施,然而目前尚无药剂被登记用于该病害的防治。本研究以来自我国各褐斑病发生区的54个代表菌株构成一个群体,应用刃天青(resazurin,RZ)显色法测定病菌群体对新烟酰胺类杀菌剂啶酰菌胺、氟酰胺和噻氟酰胺,以及吡啶类杀菌剂氟啶胺的敏感性。结果表明,该病菌种群孢子萌发对啶酰菌胺、氟酰胺、噻氟酰胺和氟啶胺而言都是野生的敏感群体,尚未发现抗药性菌株,平均EC50值分别为0.467 7μg/mL、0.010 3μg/mL、0.061 9μg/mL和0.010 0μg/mL。广东和浙江菌株对啶酰菌胺较不敏感,重庆菌株对噻氟酰胺更敏感,而对氟酰胺和氟啶胺的敏感性则与菌株的地理来源无关。柑橘褐斑病菌种群对这4种杀菌剂敏感性的确定,可为选择药剂防治ABS提供依据,并为这些药剂推广后的抗药性监测提供基础研究。展开更多
文摘Alternaria brown spot is considered the main disease of tangerines in the State of Paraiba. The objective of work was to evaluate vegetal tinctures from bitter melon (<em>Momordica charantia</em>) and guava (<em>Psidium guajava</em>) leaves, as an alternative control for Alternaria brown spot in tangerine. The effects of vegetal tinctures were tested in leaves and fruits (detached) of tangerine “Dancy” inoculated with tangerine pathotype of <em>Alternaria alternata</em>. The effect of tinctures on mycelium growth and spore germination of the pathogen was tested. Tinctures at 20% concentration promoted reduction of disease severity. A reduction of 80% in the diameter of leaf lesions was observed for bitter melon tinctures and 75.3% for guava tinctures. In fruits, the reduction was 48.4% (bitter melon tinctures) and 43.3% (guava tinctures). Guava tinctures, starting at a concentration of 5%, inhibited 100% of mycelium growth of tangerine pathotype of <em>A. alternata</em>, while the use of bitter melon tinctures inhibited 100% of mycelium growth starting at a concentration of 10%. The greater sensitivity to tinctures observed when these were added to the culture medium when compared to inoculation in leaves and fruits may be explained due to the higher exposition of the pathogen to the active principle when the vegetal tinctures were added to the culture medium, than when tinctures were sprayed over the vegetal surface in fruits and leaves. The number of germinated spores decreases 76.7% and 82% when using tinctures from guava and bitter melon (20%). Tinctures from bitter melon and guava are potential tools for alternative management of the Alternaria brown spot in tangerine “Dancy”.
