In vivo efficacy of new molecules of fungicides against Eumusae leaf spot disease of French plantain cultivar Nendran (Musa AAB)

The French plantain cultivar, Nendran ( Musa AAB) is the most widely and commercially cultivated variety of banana in Kerala. But this cultivar is highly susceptible to foliar fungal diseases especially leaf spot diseases. Among the leaf spot diseases, Sigatoka leaf spot caused by Mycosphaerella spp. poses a serious threat to banana cultivation. The studies on characterization of the pathogen associated with Sigatoka leaf spot disease complex in Kerala revealed that the predominant leaf spot disease is Eumusae leaf spot disease caused by Mycosphaerella eumusae . With an objective to develop a fungicidal recommendation for the sustainable management of this disease, a field experiment was conducted during 2016-17 at Banana Research Station, Kannara by evaluating the efficacy of six chemical fungicides viz., trifloxystrobin (25%) + tebuconazole (50%) (Nativo® – 0.4g/L), propiconazole (Tilt® – 1ml/L), copper hydroxide (Kocide® – 2g/ L), pyraclostrobin (Headline® – 1g/L), hexaconazole (5%) + captan (70% (Taqat® – 2g/L) and Bordeaux mixture (1%). All the chemical fungicides used in the study were found to be superior compared to unsprayed control. However, there was a variation in the efficacy between the treatments. The foliar application of the systemic fungicide trifloxystrobin + tebuconazole (0.4g/L) recorded the lowest per cent disease severity (PDS) of 15.43 per cent with the eighth leaf of the plant as the youngest leaf spotted (YLS) and the maximum disease development time (DDT) of 50.66 days. Among the contact fungicides evaluated, the lowest per cent disease severity of 16.65 per cent was recorded in plants sprayed with copper hydroxide which recorded DDT of 49.33 days and YLS of 7.29. The analysis of fungicide residue in the fruits revealed that there was no residue of the chemicals left in the fruit. The study revealed that four times foliar spraying of systemic fungicide, trifloxystrobin + tebuconazole (0.4g/L) or contact fungicide, copper hydroxide (2g/L) starting from the initial appearance of the disease on the lowest leaves of 75 per cent plants was safe and effective for the management of Eumusae leaf spot disease of banana.