~ 366 ~ The Pharma Innovation Journal 2021; 10(10): 366-370 ISSN (E): 2277- 7695 ISSN (P): 2349-8242 NAAS Rating: 5.23 TPI 2021; 10(10): 366-370 © 2021 TPI www.thepharmajournal.com Received: 16-08-2021 Accepted: 18-09-2021 N Hinduja M.Sc. (Ag.) Plant Pathology, Naini Agricultural Institute, Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, Uttar Pradesh, India Sobita Simon Professor and Head, Department of Plant Pathology, Naini Agricultural Institute, Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, Uttar Pradesh, India Abhilasha A Lal Assistant Professor, Department of Plant Pathology, Naini Agricultural Institute, Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, Uttar Pradesh, India Corresponding Author: N Hinduja M.Sc. (Ag.) Plant Pathology, Naini Agricultural Institute, Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, Uttar Pradesh, India Effect of selected bio-resources on purple blotch disease of onion (Allium cepa L.) N Hinduja, Sobita Simon and Abhilasha A Lal Abstract Onion (Allium cepa L.) which is also called as “bulb onion”, “Queen of kitchen” or “Princess of vegetables”, is one of the important cultivated crops belonging to the genus Allium and family Amaryllidaceae. Purple blotch of onion which is caused by Alternaria porri is major disease in the onion. The silkworm excreta, Trichoderma viride, Pseudomonas fluorescens and neem oil were tested under field conditions during Rabi 2020- 2021 for their efficacy against the disease and growth & yield parameters. A survey was conducted during Rabi 2020 to know the severity of purple blotch of onion in farmer’s fields in Anantapur district of Andhra Pradesh. Eight villages were selected in the district and in each village five fields were surveyed. The disease severity ranged from 23.22 to 48.39 per cent irrespective of location surveyed. The disease severity was least in Sanipalli village (23.22%) during December 2020 and highest in Venkatapuram village (48.39%) during the month of December 2020. Among the treatments the plant height (cm) at 90 DAT significantly increased in T4 – Trichoderma viride+ Pseudomonas fluorescens+ silkworm excreta (38.0 cm) followed by T1 – Pseudomonas fluorescens+ silkworm excreta (28.6 cm). The weight of bulb significantly increased in T4 – Trichoderma viride+ Pseudomonas fluorescens+ silkworm excreta (53.6 gm) followed by T3 – neem oil (46.3 gm). The bulb diameter (3.6) and yield (15.3 q/acre) significantly increased in T4 – Trichoderma viride+ Pseudomonas fluorescens+ silkworm excreta followed by T2 – Trichoderma viride+ silkworm excreta. Disease intensity (%) at 90 DAT (27.8%) significantly decreased in T4 – Trichoderma viride+ Pseudomonas fluorescens+ silkworm excreta followed by T2 – Trichoderma viride+ silkworm excreta. Higher gross return value (Rs. 27,134.1/acre), net return value (Rs. 14,334/acre), and B:C Ratio (2.11) was found in the treatment T4 – Trichoderma viride+ Pseudomonas fluorescens+ silkworm excreta as compared to untreated check control T0 – (1.20). Keywords: Alternaria porri, neem oil, Pseudomonas fluorescens, purple blotch of onion, Trichoderma viride Introduction Onion (Allium cepa L.) which is also called as “bulb onion”, “Queen of Kitchen” or “Princess of vegetables”, is one of the important cultivated crops belonging to the genus Allium and family Amaryllidaceae and originates from Western Asia, i.e. Turkestan and Afghanistan. Onions are grown in every part of the world where plants are cultivated and can be grown from seeds, bulbs or sets. It shows great variation in many characteristics such as size, colour, shape and pungency (Griffiths et al., 2002) [8] . Onion has great economic importance due to its medicinal and dietetic values (Chakraborty et al., 2015) [4] . Onion contains a lachrymatic agent, a strong antibiotic in addition to fungicidal, anti-bacterial, anti-cholesterol, anti-cancer and anti-oxidant components such as quercetin (Baghizadeh et al., 2009) [2] . In addition, it is to be rich in phytochemicals especially flavonols which are of medicinal (Javadzadeh et al., 2009) [11] . Onion is an extensively grown biennial bulb crop, with world production of 93,226,400 tonnes produced per year. China and India are the primary onion growing countries. Maharashtra and Karnataka ranked the highest for the production of onions during the measured time period. The major onion producing states are Maharashtra, Madhya Pradesh, Karnataka, Rajasthan, Bihar, Gujarat, Andhra Pradesh, Haryana, West Bengal and Uttar Pradesh in the country. These states account for almost 90% of the total onion production in the country (Anonymous, 2020) [1] . Among the diseases, Purple blotch (Alternaria porri) is one of the major constraints in onion cultivation. The causal organism of disease is Alternaria porri. The symptoms are water- soaked lesions with small white centres. Lesions usually appear on older leaves and become purple with yellow concentric rings on the margins as the disease progresses.