Bio-efficacy of Different Plant Extracts against Ascochyta pisi Causing Blight of Pea (Pisum sativum L.) under Laboratory and Field Conditions

Abstract

Pea (Pisum sativum L.) is an important cool-season legume crop native to northwest to southwest Asia and is widely cultivated in temperate regions. Ascochyta blight, caused by Ascochyta pisi, is a serious disease affecting all growth stages, leading to reduced plant growth, biomass, and seed yield, particularly through decreased seed weight and the number of seeds per pod. The disease is characterised by brown-to-black lesions on leaves, stems, petioles, and pods, which later coalesce into large blighted areas. To develop an eco-friendly management strategy, various botanical extracts, namely Neem (Azadirachta indica), Aak (Calotropis procera), Garlic (Allium sativum), Datura (Datura stramonium), Parthenium (Parthenium hysterophorus), and Giloy (Tinospora cordifolia), were evaluated under both in vitro and in vivo conditions for their efficacy against the disease. All extracts significantly inhibited the growth of the pathogen at 7 days after inoculation. Neem leaf extract was the most effective, recording 88.89% and 100% mycelial growth inhibition at 5% and 10% concentrations, respectively. Garlic clove extract showed moderate inhibition (42.22% and 63.33%), whereas giloy stem extract was the least effective (15.56% and 27.78%). All plant extracts evaluated under in vitro conditions were further tested for their efficacy in managing the disease under field conditions. Under in vivo conditions, all treatments significantly reduced disease intensity compared with the untreated control, indicating their potential role in the eco-friendly management of the disease. Neem leaf extract resulted in the highest disease reduction (54.31%), followed by garlic (23.91%), whereas giloy showed the least effect (7.91%). The study highlights the potential of neem-based plant extracts as an effective, economical, and environmentally safe approach for managing Ascochyta blight of pea.