Powdery mildew is a foliar disease of all plants in the cucurbit family. The talc-like symptoms on leaves are relatively easy to identify (Figure 1). More about powdery mildew of cucurbits can be found at this link https://vegcropshotline.org/article/powdery-mildew-of-cucurbits-2/. The remainder of this article is an update.
Figure 1. Powdery mildew causes talc-like lesions on pumpkin leaves.
There are several systemic fungicides which are recommended for powdery mildew of cucurbits. These include: Aprovia Top®, Fontelis®, Luna Experience®, Merivon®, Procure®, Quintec®, Rally® and Torino®. Recently, fungicide resistance to the product Torino® was discovered in eastern New York. I don’t know if the strains of the powdery mildew fungus we have in Indiana are resistant to Torino® or not. Growers should scout their fields for the effectiveness of Torino® and other products. It is always best to alternate systemic fungicides for the management of powdery mildew of cucurbits. If possible, alternate between 3 or 4 products that have different modes of action. Not only does this practice lessen the possibility of the creation of fungicide resistant strains, but my experience is that such a fungicide alternation usually results in the best disease control.
Do not hesitate to contact me with more questions about powdery mildew of cucurbits or the effectiveness of fungicides.