Effectiveness of Some Biological and Chemical Fungicides to Control Powdery Mildew in Zucchini

Abstract

Powdery mildew is one of the most devastating diseases affecting zucchini (Cucurbita pepo L.), leading to substantial economic losses by reducing plant vigor, yield, and fruit quality in open-field cultivation. The primary causal agents are Erysiphe cichoracearum and Podosphaera xanthii (syn. Sphaerotheca fuliginea) common pathogens of cucurbit crops. Traditional management has relied heavily on chemical fungicides, however, their continuous use has led to the development of resistance, environmental pollution and health concerns regarding pesticide residues. Therefore, the search of safe and sustainable alternatives has become a priority for integrated disease management. The objective of the current research was to determine the efficacy of three chemical fungicides (Baymert, Heros, and Pancho) and two biological control agents (Trichoderma sp. and Penicillium sp.) to decrease infections of powdery mildew and to enhance the yield of zucchini under field conditions in Jisr al-Shughur, Syria, during the 2024 season. E. cichoracearum and P. xanthii were artificially inoculated into plants and disease severity was evaluated 3, 7 and 12 days after treatment. Findings indicated that powdery mildew had a quick initial control with the use of chemical fungicides. Three days later, Heros recorded a control efficiency of 56.2%, after spraying. However, they were not effective over time, especially in the case of Pancho, which had reduced to only 18.1% control by day 12. Conversely, biological control agents proved to act later but to have lasting effects. Trichoderma sp. recorded the highest control efficiency among the biological treatments at 55.4% after 12 days and produced the highest vegetative yield, reaching 116.8 g/plant after 15 days, compared with 29.5 g/plant in the untreated control. The second-best performer in terms of vegetative yield (89.6 g/plant) was Heros, and Penicillium sp. gave moderate but consistent control. Such results are in line with the fact that chemical fungicides are only capable of short-term suppression, but they do not persist effectively in the field. Biological control agents, specifically Trichoderma sp, are a better long-term solution, with long-term disease control and increased growth of plants and yield advantages. The research highlights the importance of the inclusion of biological control as an idea in sustainable powdery mildew management measures in zucchini production in reducing the usage of synthetic fungicides and in making agricultural systems safer and cleaner.