Surgery or surgical defolation in ‘Grand Naine’ banana in the control of black Sigatoka in the state of Rio de Janeiro

Abstract ‘Grande Naine’ banana (Musa acuminata - AAA) in the municipality of Angra dos Reis (RJ) has been affected by the Black Sigatoka agent, fijiensis Mycosphaerella(current name Pseudocercospora fijiensis); causing losses to local producers, mostly small producers and low-income producers. Since Black Sigatoka was reported in the mentioned municipality, it was aimed to determine control efficiency through surgical measurement or surgical defoliation and to evaluate its effect on banana productivity characteristics. For this purpose, treatment was designed in the form of completely randomized blocks containing three blocks, each block with five plants with treatment (Surgery) and five plants without treatment (Control), in a total of 30 plants with fungal infection. Treatments were performed every 15 days with monthly severity assessments (Weighted Mean of Infection - MPI) by the method of Stover modified by Gauhl. The results obtained at the end of the trial showed significant differences in all variables (Severity, youngest leaf spotted, bunch weight and fruit size), and treatment with surgery provided reduction in severity (MPI) around 58%, thus confirming that plants received adequate treatment according to the results obtained for this methodology, and, contributing to the increase of the healthy leaf area in the youngest leaves, whereas in plants without surgery (Control), severity increased by 14.8% in comparison to the initial MPI evaluation, consequently having a smaller healthy leaf area for the accomplishment of photosynthesis and other physiological processes. In production variables bunch weight, fruit size and number of fruits, differences were significant (Pr> F = 0.0001), reaching an increase in yield of up to 300% when compared to Control. It is therefore an effective method for the control of phytopathogen black sigatoka unpublished in the state of Rio de Janeiro and that will bring direct benefits for Family Agriculture in the region of incidence of this banana disease.

摘要：巴西里约热内卢州安格拉杜斯雷斯市的大矮蕉（Grande Naine，Musa acuminata - AAA）遭受了黑条叶斑病（Black Sigatoka）病原菌斐济假尾孢菌（Pseudocercospora fijiensis，原名为Mycosphaerella fijiensis）的侵染，导致当地以小型种植户、低收入种植户为主的蕉农蒙受经济损失。自安格拉杜斯雷斯市首次报道该病害以来，本研究旨在通过外科处理（或手术式摘叶）法确定其防控效率，并评估该方法对香蕉产量性状的影响。为此，实验采用完全随机区组设计，共设置3个区组，每个区组包含5株经外科处理的植株与5株未处理的对照植株，总计30株感染病原菌的香蕉植株。每15天进行一次处理，每月采用Gauhl修正的Stover法评估病害严重度（病害加权平均指数，Weighted Mean of Infection - MPI）。试验结束后所得结果显示，所有观测变量（病害严重度、最幼显病叶片、果穗重量及果实大小）均存在显著差异；外科处理组的病害加权平均指数（MPI）降低约58%，证实该方法可对植株实施有效防控，同时可增加最幼叶片的健康叶面积。而未处理的对照组植株，其病害严重度较初始MPI评估值升高14.8%，因此可用于光合作用及其他生理过程的健康叶面积更小。产量相关变量（果穗重量、果实大小及果实数量）同样存在极显著差异（P>F=0.0001），与对照组相比，处理组的产量最高可提升300%。综上，该外科防控法是针对黑条叶斑病的有效手段，目前在里约热内卢州尚无相关报道，可为该香蕉病害发生区域的家庭农业带来直接收益。