Assessment of factors contributing fruit drop in Nagpur mandarin (Citrus reticulata blanco) grown in central India

A survey study was conducted in the eastern Maharashtra region during the Ambe Bahar (January–February flowering) seasons of 2022 and 2023 to assess the factors contributing to fruit drop in Nagpur mandarin (Citrus reticulata Blanco). The research focused on quantifying the extent of fruit drop, identifying associated factors, and evaluating the soil and plant health status of the surveyed orchards. A combination of social surveys and field observations was carried out across five distinct mandarin cultivation sites in the Vidarbha region of Maharashtra. The analysis revealed that fruit drop is a significant concern, leading to a yield reduction of over 55% in the surveyed orchards. Two primary causes of fruit drop were identified as pathological factors and plant nutritional deficiencies. Pathological factors were mainly attributed to Colletotrichum spp., a phytopathogenic fungus that thrives under specific environmental conditions. Meanwhile, nutritional deficiencies weakened plant health, making trees more susceptible to fruit drop. Phytopathogenic fungi were isolated from dropped fruits, with Colletotrichum spp. being the majorly identified pathogen. Fruit drop intensity varied at different stages of fruit development, with an incidence of 12% during the bloom stage, 22.5% during the fruit growth stage (June– July), and 65.5% during the pre-harvest stage (August–October). The findings suggest that pre-harvest fruit drop disease (PAFD) is likely influenced by fungal infections caused by Colletotrichum spp., further exacerbated by inadequate soil moisture and nutrient deficiencies. By evaluating key factors such as soil moisture, plant nutrition, hormone levels, and disease conditions, effective management strategies can be developed to enhance the production and minimize fruit drop in Nagpur mandarin orchards.