Induction of resistance in onion against purple leaf blotch disease through chemicals

doi:10.35495/ajab.2020.01.039

Abstract

Highlights

Onion (Allium cepa L.) is one of the most important bulb crop, among all vegetables (Teshika et al, 2019) that belongs to family Amaryllidaceae genus Allium (Akbar, 2020)
Most economical way for the management of purple blotch is the use of resistant varieties, but due to scarcity of resistant varieties, if the disease appeared in the field in epidemic form, farmers have only one option, which is the use of chemical fungicides towards purple blotch of onion, as it is quick in action and available
Chlorostrobin was proved most effective by causing 62.05 % reduction in disease severity followed by Nanok, Shincar, Cabrio Top (Metiram + Pyraclostrobin), Thrill (Bismirthazole), which expressed up to 50% reduction and nine fungicides namely Jalwa (Penthiopyrad), Success40 WSP (Chlorothalonil + Metalaxyl), Cytrol, Copride, Alliette (Fosetyl Aluminium), Flu Max, Tilt, Rally (Myclobutanil) and Topsin M causes up to 40 % reduction in disease while four fungicides Copper oxychloride (Copper) and Score (Difenaconazole), Topas (Penaconazole + Difenaconazole), Antracol, controlled more than 30% disease and remaining five fungicides Melody due (Propineb + iprovalicarb), Dithane M (Dithiocarbamates), Curzate M, Sulphax and Ridomil gold (Mancozeb + Metalaxyl) controlled less than 20% disease respectively as compared to control

Summary

Introduction

Onion (Allium cepa L.) is one of the most important bulb crop, among all vegetables (Teshika et al, 2019) that belongs to family Amaryllidaceae genus Allium (Akbar, 2020). Onion plays a crucial role in different industries including food and medicine. It contains carbohydrates (8.7g), soluble proteins (9.22-13.21g), vitamin C (45.07mg) and 88.65% water in 100gram sample of fresh onion (Sami et al, 2021), while onion contains natural beneficial. Compounds including thiosulfinates, saponins, polyphenols (Golubkina and Gianluca, 2020) and flavonoids (especially in red onion) (Akbar, 2020). 99.9 million tonns worldwide production was recorded from an area of 5.19 million hectares (FAO, 2019). While in Pakistan 2.06 million tonnes production was recorded from an area of 146.1 thousand hectares (GOP, 2020). Onion crop is susceptible to attack by various fungal, bacterial, and viral diseases. Purple blotch is most destructive and damaging foliar disease of onion which is caused by a fungal pathogen

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