SOURCES AND CONCENTRATIONS OF CUPRIC FUNGICIDES FOR THE CONTROL OF CITRUS BLACK SPOT1

ABSTRACT Citrus black spot (CBS) is a severe disease for citriculture in the São Paulo State, Brazil. Part of its management is focused on chemical control using cupric fungicides and strobilurins. The objective of the present work was to evaluate the efficacy of three sources and three concentrations of cupric fungicides (copper hydroxide, copper oxychloride and cuprous oxide). Orange fruits of the Pera cultivar were bagged in the plants and the treatment with cupric fungicide was applied. The fruits were inoculated (by spray) with Phyllosticta citricarpa (1×104 conidia mL-1) after 0, 7, 14, 21, and 28 days, and bagged again. The evaluation of incidence and severity was did at the harvest time of fruits. A second experiment was conducted under natural infection with the same treatments, consisting of application of fungicides at the stages F1 (petal fall) and F2 (fruits with diameter of 1 cm), using mechanized sprayer with mean flow of 7.35 L solution plant-1. Subsequently, all treatments received four applications of azoxystrobin (30 g ha-1), plus mineral oil at 0.25%. Four monthly evaluations were done to determine the CBS incidence and severity. The initial applications with cupric fungicides are essential for the control of CBS; the fungicide copper hydroxide showed the best control of CBS with the lowest rate of metallic copper (43.7 g of Cu++ 100 L-1) in both experiments, regardless of the conduction conditions.摘要：柑橘黑点病（Citrus black spot, CBS）是巴西圣保罗州柑橘种植业的重大病害。其防控工作部分聚焦于使用铜制剂杀菌剂与甲氧基丙烯酸酯类杀菌剂（strobilurins）开展化学防治。本研究旨在评估三种铜制剂杀菌剂（氢氧化铜、氧氯化铜与氧化亚铜）的三种施用浓度的防控效果。供试的佩拉（Pera）品种橙果在植株上完成套袋后，施加铜制剂杀菌剂处理。分别于处理后0、7、14、21、28天，通过喷雾接种柑橘黑点病病原菌（Phyllosticta citricarpa，浓度为1×10^4个分生孢子·毫升^-1），接种后再次套袋。于果实采收期开展病害发病率与严重度调查。第二项试验采用自然侵染模式，设置与前述一致的药剂处理方案，分别在F1（花瓣脱落期）与F2（果实直径1 cm期）两个时期喷施杀菌剂，使用平均药液流量为7.35升·株^-1的机动喷雾器施药。随后所有处理组均喷施四次嘧菌酯（azoxystrobin，30克·公顷^-1），并添加0.25%的矿物油。每月开展一次调查，共四次，用于统计柑橘黑点病的发病率与严重度。研究结果表明：初始施用铜制剂杀菌剂对柑橘黑点病防控至关重要；在两项试验中，无论试验实施条件如何，氢氧化铜杀菌剂在最低金属铜施用量（43.7克Cu²+·100升^-1）下，均展现出最优的病害防控效果。