Untimely rains lead to surge in fungal growth on onions
Onions entering vegetable markets in Bengaluru in recent days are covered with black fungus or mould, as untimely rains hit several regions before the southwest
Onions entering vegetable markets in Bengaluru in recent days are covered with black fungus or mould, as untimely rains hit several regions before the southwest monsoon set in. This has also led to such onions being sold at lower rates. While unaffected onions are being sold at ₹20 to 25 per kg, those affected by fungus are being sold for ₹15. Karnataka’s annual average production of onions is more than two million tonnes, but rains play an important role in cultivation. According to horticulture department officials, last year onions were grown on 1,52,000 hectares in the State, and every year the number of growers is increasing as they get returns within three to four months, unlike other crops. K. Dhanraj, Joint Director of Horticulture (Vegetables), explained, “Black mould on onions is a post-harvest disease that is most prevalent during the rainy season, when there is higher humidity in the atmosphere, especially in Bengaluru. It is popularly known as Aspergillus niger. This post-harvest disease is seen in the Kharif harvest of onions. During the Rabi season, the harvest undergoes a process of curing when weather conditions are favourable, which helps dry the outer skin and prevents fungal growth during long-term storage.” He added, “Such post-harvest diseases are not seen in dry weather conditions.
Farmers make the most of dry weather and sunlight by spreading the onions. However, in rain-affected regions, fungal blight develops on the onions, and they also begin to rot from the inside. At present, in places like Challakere and Hosadurga, farmers have started sowing seeds for onion cultivation after the State received a few days of rain and the soil became softer. Districts like Vijayapura, Bagalkot, Gadag, and Koppal, among others, are known for growing onions.” Dhanraj advised that farmers should maintain ventilated storage facilities with a minimum room temperature of 10°C. “Since it is both a Kharif and Rabi crop, the sowing season for the Kharif crop in Karnataka is in June, and it is harvested by the end of September. The sowing season for Rabi onion is in October and it is harvested by the end of January or the beginning of February. The curing process usually takes 14 to 20 days after harvesting. Fungus appears if onions are harvested and packed within a day or two without adequate time for curing, but it develops gradually,” he added. Meanwhile, Shalini M., associate professor, Department of Horticulture, said, “Such onions in the market have become more prevalent since early 2025 in rain-affected parts of Karnataka, as there is higher humidity in the atmosphere.
The BriefWire