Brown rot is a common and devastating disease of different fruits and vegetables. During 2018, a profound brown rot was observed on lemon (Citrus lemon L.) in Islamabad, Pakistan and adjacent areas. This study was designed to identify disease causing pathogen of this disease. Diseased lemon fruit were collected from the orchards and disease causing pathogen was isolated. The morphology of pathogen was examined under stereoscope and compound microscope and the pathogen was identified as Alternaria alternata. For the molecular characterization of this fungus, 18S ribosomal RNA gene was sequenced and its phylogenetic analyses were performed. BLAST analysis revealed 100% similarity with A. alternate NS8, 18S ribosomal RNA gene, partial sequence (MK346034.1). This is the first report of brown rot of lemon, caused by A. alternata in Pakistan. For ecofriendly control of this disease, extracts of indigenous medicinal plants including Justacia adhatoda, Azadriachta indica, Foeniculum vulgare and Mentha spicata were used. In these plant extracts, the presence of various functional groups such as alcohols, carboxylic acids, esters, alkanes and alkenes was revealed by Fourier transform infrared spectroscopy (FTIR). Both in vitro and in vivo assay showed the significant role of aqueous plant extracts to suppress the growth of A. alternata. Among these phytoextracts, A. indica proved to be the most efficient in suppressing the growth of the pathogen and controlling disease. Findings of this study suggest the use of these plant extracts for environment friendly control of fruit rot disease.

褐腐病是各种水果和蔬菜的常见和破坏性疾病。在2018年期间，在巴基斯坦伊斯兰堡和邻近地区的柠檬（Citrus lemon L.）上观察到了深褐色腐烂。本研究旨在确定引起该病的病原体。从果园中收集病态的柠檬果实，并分离出引起疾病的病原体。用立体镜和复合显微镜对病原菌的形态进行了鉴定，鉴定为链格孢菌（Alternaria alternata）。为了对该真菌进行分子鉴定，对18S核糖体RNA基因进行了测序，并进行了系统发育分析。BLAST分析显示100％的相似性A.备用NS8，18S核糖体RNA基因，部分序列（MK346034.1）。这是巴基斯坦A. alternata引起的柠檬棕褐色腐烂的首次报道。为了对这种疾病进行生态友好的控制，使用了本地药用植物的提取物，其中包括：Justacia adhatoda，Azadriachta indica，Foeniculum vulgare和Mentha spicata。在这些植物提取物中，通过傅立叶变换红外光谱（FTIR）揭示了各种官能团（如醇，羧酸，酯，烷烃和烯烃）的存在。二者在体外和体内试验表明含水植物提取物的作用显著抑制的生长链格孢。在这些植物提取物中，事实证明，印度。草在抑制病原体的生长和控制疾病方面是最有效的。这项研究的结果表明，将这些植物提取物用于对水果腐烂病的环境友好控制。