BIOLOGICAL CONTROL OF Alternaria citri CAUSING BLACK ROT OF CITRUS IN PAKISTAN

Abstract

Citrus is a valuable fruit crop consumed mainly as fresh fruit or juice, known for its nutritional and health benefits due to its content of phytochemicals, ascorbic acid, limonoids, carotenoids, vitamin B complex, and related nutrients. However, citrus production suffers significant losses due to various diseases, with Alternaria citri causing severe damage through brown leaf spot, which deteriorates the fruit's quality. An experiment was conducted to develop a management strategy against Alternaria citri. Samples were collected from the field and analyzed in the lab. Pathogen isolation was done using the poisoned food technique, and different vitamins and plant extracts were assessed for their effectiveness against pathogen growth. Cloves showed the most significant inhibition of fungal growth, followed by mint, cinnamon, neem, and ginger. In a field experiment, thiamine treatment resulted in the lowest disease incidence, followed by pyridoxine and niacin. Environmental factors such as temperature, relative humidity, rainfall, and wind speed were recorded during the growth period. The data showed that relative humidity, temperature, and wind speed were positively correlated with disease incidence, while rainfall had a negative correlation. The experiment was conducted under Completely Randomized Design (CRD) and Randomized Complete Block Design (RCBD), and statistical analysis confirmed the efficacy of vitamins and plant extracts against Alternaria citri.