Background and Objective: Pea (Pisum sativum L.) was attacked by many foliar diseases. Downy mildew, powdery mildew and rust are the most common diseases that affect the quantity and quality of this crop. To control these diseases, certain natural organic acids, e.g., citric, benzoic, salicylic, boric, sorbic acids and also coumarin were foliar sprayed to examine the possibility of avoiding the adverse effect of biotic stress. Materials and Methods: The experiment was conducted at Kafr-El-Dwar district, Beheira Governorate, Egypt during 2 successive summer seasons of 2019 and 2020 to evaluate pea plants foliar spray with some organic acids and coumarin at the rate of 0.25 and 0.50% against some foliar diseases. Results: The results proved that citric and benzoic acids at 0.50% induced the highest reduction of downy, powdery mildew and rust, while coumarin recorded the lowest reduction at the same concentration and other tested materials came moderately. Moreover, all tested substances gave clear increases in crop parameters and alleviated the harmful effects of biotic (diseases) stress. Acceleration in the recovery in terms of enhancing photosynthetic pigments, indole acetic acid, phenolic, some compatible solutes and antioxidant content was recorded. Also, a positive variation in anatomical structure, e.g., the leaflet blade thickness, upper and lower epidermal layers, vascular bundles, midrib zone, palisade and spongy tissues was noticed. Conclusion: Conclusively, foliar spraying with tested materials alleviated the harmful effects of biotic stress and accelerated the recovery and improved pea plants productivity.