Serambi Journal of Agricultural Technology, Vol. 3 No.1Hal 1 – 8 2021 | 1 Serambi Journal of Agricultural Technology (SJAT) http://ojs.serambimekkah.ac.id/index.php/sjat Vol. 3 No. 1 Thn. 2021 E-ISSN: 2684-9879 S J A T Macroscopic Diagnosis of Plant Diseases Caused by Pathogenic Microorganism Annisyah Nasution 1 , Vivi Mardina 1* , Sara Gustia Wibowo 1 1 Program Studi Biologi, Fakultas Teknik, Universitas Samudra, Jl. Prof.Syarief Thayeb, Meurandeh, Langsa Lama, Kota Langsa, Aceh, Indonesia 24416 *email: vmardina@unsam.ac.id Article Info Article history: Received: 02/27/2021 Received in revised: 05/21/2021 Accepted : 06/11/2021 Abstract From a biological point of view, plant diseases are deviations from internal traits that cause plants to not be able to carry out normal growth activities. Plant diseases in the field can be identified based on signs and symptoms of diseases that appear. This study aims to determine how to diagnose macroscopically the symptoms of diseases that arise due to pathogenic microorganisms on plants. This research was conducted in 3 stages which included the location survey, observation, and primary data collection stages. The method for primary data collection is done by direct observation, namely direct observation of samples and documented. Data were analyzed using the formula to calculate the percentage and intensity of disease attacks on plants. The results obtained were as many as 3 plant species (Capsicum sp, Solanum escelentum, Oryza sativa) from 12 plants which were observed to be attacked by pathogenic microorganisms with a percentage amount (22,45 %, 58,97%, 9%). Obtain 4 types of pathogenic microorganisms that attack plants, namely Gemini virus that causes leaf curling in Capsicum sp plant, Pyricularia oryzae fungus which causes leaf blast in Oryza sativa plants, the fungus Alternaria solani causes dry spot and Rhizoctonia solani fungus which causes leaf blast in Oryza sativa plants, the fungus Alternaria solani causes leaf dry spot and Rhizoctonia solani fungi that cause fruit rot in Solanum escelentum. Keywords: Diagnosis, Microscopic, Microorganisms, Pathogens. Diagnosis Makroskopik Penyakit Tanaman Yang Disebabkan Mikroorganisme Patogen Abstrak Penyakit tanaman adalah penyimpangan dari sifat internal yang menyebabkan tanaman tumbuh abnormal. Penyakit tanaman di lapangan dapat dikenali berdasarkan tanda/gejala penyakit yang muncul. Penelitian ini bertujuan untuk mendiagnosa penyakit tanaman secara makroskopik disebabkan mikroorganisme patogen di Dinas Pangan Pertanian dan Perikanan Kelautan Kota Langsa. Metode penelitian dilakukan secara direct observation. Data dianalisis menggunakan rumus penghitungan persentase dan intensitas serangan penyakit pada tanaman. Hasil yang diperoleh adalah sebanyak 3 spesies tanaman (Capsicum sp, Solanum escelentum, Oryza sativa) dari 12 spesies yang diamati terserang mikroorganisme patogen dengan jumlah persentase yaitu 22,45%, 58,97%, dan 9%). Berdasarkan pengamatan makroskopis, diduga terdapat 4 jenis mikroorganisme patogen yang menyerang tanaman yaitu (1) virus Gemini penyebab keriting daun pada tanaman Capsicum Sp, (2)