Control of Colletotrichum truncatum causing anthracnose/pod blight of soybean by aqueous leaf extracts, biocontrol agents and fungicides

Abstract

A study was conducted in the of Department Plant Pathology, Marathwada Agricultural University, Parbhani, Maharashtra during 2009 to 2010 to control Colltotrichum truncatum causing anthracnose / pod blight of soybean with plant extracts and bio-agents . All the nine aqueous leaf extracts and four species of antagonist Trichoderma evaluated in vitro were found effective against C. truncatum and recorded significant inhibition of the test pathogen over untreated control. However, T. viride was found most effective and recorded 18.53 mm mean colony diameter and recorded significantly highest growth inhibition (79.40 %) of the test pathogen. This was followed by T. hamatum and Pseudomonas fluorescens with 73.74 and 69.31 per cent growth inhibition, respectively. Of the aqueous leaf extracts evaluated, Garlic recorded significantly highest growth inhibition (81.82%) of the test pathogen. The second and third best plant extracts found were Tulsi (65.17 % inhibition) and Onion (60.31% inhibition) both of which were on par. Among the nine fungicides, Carbendazim recorded least mean colony diameter (7.52 mm) and highest inhibition (91.63 %) of mycelial growth of the test pathogen over untreated control, followed by Mancozeb which recorded mean colony diameter of 10.38 mm and mean mycelial growth inhibition of 88.45 per cent. In field, Carbandazim (@ 0.1%) recorded least mean disease intensity (19.55%), mean pod infection (9.63%), highest seed yield (2605 kg/ha) and test weight (14.33 g). It also recorded highest reductions in the disease intensity (40.73%), pod infection (75.73%) over unsprayed control followed by Mancozeb (@ 0.1%) which recorded the minimum mean disease intensity (21.50%) pod infection (10.78%). Considering incremental cost: benefit ratio (ICBR), the most economical treatment which recorded highest cost: benefit ratio was the fungicide Carbendazim (C:B ratio, 1:14.45) followed by Carbendazium + Mancozeb (C:B ratio, 1:8.92).