Basil is a commonly used to make pesto and tomato sauce and is a popular ingredient in Italian and Thai recipes. It’s also often used in salads or sprinkled on tomatoes.

Margaret McGrath, an associate professor of plant pathology at Cornell University, said the fungus is likely more of a problem for home gardeners and herb farmers who may not have access to fungicides that are available to larger commercial growers.

“We think it’s moving around each year, surviving over the winter and then moving north during the summer,” McGrath said.

The relatively recent emergence of the fungus means many growers don’t know about it, McGrath said.

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