By Clint Thompson
North Carolina (N.C.) vegetable growers should be mindful that cucumber downy mildew has been confirmed on cucumber plant samples from a research plot at the Mountain Research Station in Haywood County, North Carolina. It was detected on July 30.
Inga Meadows, N.C. State Extension Associate in Vegetable and Herbaceous Ornamental Pathology, noted that water-soaked lesions on the undersides of leaves were observed with pathogen symptoms; gray to black spores on the underside of the leaf. Light yellow spots of lesions were observed on the upper sides of the leaves.
With the weather conditions being favorable for downy mildew development, Meadows was not surprised at its confirmation. She said growers had already been preparing for the disease with some of their fungicide applications.
“Even before downy showed up, a lot of them were already applying some of the more systemic, single-site fungicides to prevent downy mildew. They’re pretty aware that it shows up, sometime late summer,” Meadows said. “They were probably already putting products on or when they hear it show up, they start putting them on. But that’s about all they can do.”
Downy mildew was first observed this summer in the eastern part of North Carolina on June 11.
Vegetable Season
Its latest finding is significant since growers in the western part of the state will typically harvest vegetables for another 2 to 3 months. They stagger their plantings to take advantage of the growing season.
“In the mountains in western North Carolina, we primarily have your fruiting vegetables like tomato, pepper and cucurbits like cucumbers, squash, maybe some pumpkins. All of those will go on until we get our first frost which sometimes is October; sometimes it’s not until November,” Meadows said. “They’ve planted their latest crop by now.”