Effectiveness of Selected Fungicides for Control of Powdery Mildew of Pumpkin in Central Illinois, 2024

This study was conducted in Champaign, IL, to evaluate the efficacy of selected fungicides for the control of powderymildew of pumpkin, caused by the fungus Podosphaera xanthii. Seeds of jack-o-lantern pumpkin ‘Howden’ were sown on 31 May. The plots were spaced 30 ft. apart in a randomized complete block design with four replications. Applications of fungicides, at 7-day intervals, began on 22 July and ended on 26 August. Severity of powderymildew (percent total area of vines and leaves affected) was visually assessed at weekly intervals, beginning 14 July. Plots were harvested on 15 September. Powdery mildew was first observed on vines and leaves in the plots on 21 July. Severity of the disease was significantly (P = 0.05) higher in unsprayed plots compared with sprayed plots. The lowest area under the disease progress curve (AUDPC) of powdery mildew was in the plots sprayed with Quintec plus Kocide-3000 alternated with Inspire Super plus Kocide-3000.