Epidemiological Analysis of Purple Blotch Disease on Onion under the Climatic Conditions of El-Minya Governorate, Egypt | ||||
| Minia Journal of Agricultural Research and Development | ||||
| Volume 44, Issue 4, December 2024, Page 499-515 PDF (1.56 MB) | ||||
| Document Type: Original Articles | ||||
| DOI: 10.21608/mjard.2024.383546 | ||||
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| Abstract | ||||
| Purple blotch, caused by the fungus Alternaria porri, is a serious disease affecting onion crop in Egypt. This study aimed to analyze the epidemiology of purple blotch under the climatic conditions of ElMinya governorate, Egypt. Infected onion samples were collected from six areas in middle Egypt. The systemic survey was carried out to record the severity of purple blotch disease in three onion major growing districts of El-Minya governorate, Egypt, during 2020-2021 and 2021-2022 crop seasons. The survey for disease, severity, distribution, and spread was carried out at physiological maturity. Significant increase in onion purple blotch DI, DS%, the Area Under Disease Progress Curve (AUDPC) and the disease pressure was higher in the first than in second seasons. Also, there is a significant increase in both disease parameters in Giza-6 than Giza red cvs. When recorded every two weeks, from the 11th the standard week to the 22nd standard week. Based on the mean data, a multiple regression equation was developed to predict the disease. The results show that in 2021-2022, two weather parameters; the maximum temperature <20oC and relative humidity (80%), spell contributed to an increase in the infection rate. The maximum AUDPC was recorded in February-March of each season. The severity of purple blotch disease in onions varies significantly across different locations in Egypt, influenced by both environmental conditions and pathogen virulence. The variation in disease severity can be attributed to factors such as local climatic conditions, agricultural practices, and the presence of different pathogenic isolates. | ||||
| Keywords | ||||
| Purple blotch of onion; Alternaria porri; Apparent rate of infection; Area under disease progress curve; Disease Severity; Epidemiology | ||||
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