The increasing global population and rising food demand require sustainable agricultural approaches to enhance crop productivity while minimizing environmental impact. Chickpea (Cicer arietinum L.) is a vital leguminous crop and an important protein source in many developing countries; however, its production is severely affected by Ascochyta rabiei, the causal agent of Ascochyta blight. The present study evaluated the antifungal efficacy of Syzygium cumini essential oil (EO) as an eco-friendly alternative to synthetic fungicides for managing A. rabiei under both greenhouse and field conditions.

S. cumini leaves were collected from Bahauddin Zakariya University (BZU), Multan, Pakistan, and EO was extracted via hydrodistillation using a Clevenger apparatus. A pathogenic culture of A. rabiei was purified on chickpea seed meal agar, and pathogenicity was confirmed following Koch’s postulates. Ten treatments, including pre- and post-foliar EO sprays, seed treatments, and fungicide controls, were arranged in a completely randomized design (CRD) in greenhouse trials and a randomized complete block design (RCBD) in field trials.

Results revealed that S. cumini EO significantly reduced disease severity and incidence compared to the fungicide (chlorothalonil) treatments. In greenhouse experiments, EO seed treatment and preventive foliar applications achieved up to 100% disease suppression, while fungicides showed partial control (up to 25% disease severity). Under field conditions, EO seed treatment reduced disease severity to 1.79–2.11% and disease incidence to 15–17%, with substantial improvements in plant growth and yield compared to inoculated controls. EO-treated plants exhibited longer shoots and roots, more leaves, and higher yields than fungicide-treated plants.

These findings suggest that S. cumini essential oil is a promising, sustainable bio-fungicide for effective management of Ascochyta blight in chickpea cultivation, offering an environmentally safe alternative to chemical fungicides.