Pseudoperonospora cubensis, the causal agent of cucurbit downy mildew (CDM), was confirmed on butternut squash in Lenoir on July 26 of 2021. The sample was part of a sentinel plot maintained by the NC State Vegetable Pathology Lab. The plot showed 10% disease incidence and leaves showed 2% disease severity. Samples were brought to the laboratory for DNA extraction and confirmation that isolates are clade 1 Pseudoperonospora cubensis via clade-specific quantitative PCR assays developed by our lab.

Small chlorotic lesions, circular in shape, were observed on the upper surface of leaves alongside with gray sporulation on the underside, which are typical signs and symptoms of CDM (Figure 1).

Sporangiophore structures, which are distinctive of the causal agent (Pseudoperonospora cubensis), were observed on the underside of the leaf using a hand lens (Figure 2).

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