Efficacy of Selected Fungicides for Managing Powdery Mildew of Pumpkin in Central Illinois, 2025

This study was conducted in Champaign, Illinois to evaluate the efficacy of selected fungicides for managing powdery mildew of pumpkin, caused by the fungus Podosphaera xanthii. Seeds of jack-o-lantern pumpkin ‘Howden’ were sown on 30 May. A few small patches of powdery mildew were first observed on vines of unsprayed plants on 10 August. After four days, powdery mildew spots developed on lower surfaces of leaves, and then on both sides of leaves. By the end of the first week of September, almost of vines and more than 90% of leaves in unsprayed plots were covered with powdery mildew. Also, from 22 August to harvest, powdery mildew was observed on vines and leaves of plants in some sprayed plots. Severity of the disease was significantly (P = 0.05) higher in unsprayed plots compared to sprayed plots. There was no significant difference in powdery mildew severity among treatments.