This summer and fall, commercial growers, backyard gardeners, and cooks are bracing themselves, agriculture officials said.
The Rutgers Cooperative Extension in Bridgeton, Cumberland County, issued a statewide alert this month:
"All basil growers should be scouting on a daily basis and should consider adding a labeled downy mildew-specific fungicide to their program," wrote Andy Wyenandt, a specialist in vegetable pathology for Rutgers University at the center.
Organic fungicides suppress the fungus, "but we don't have a lot in the arsenal, and it won't eliminate it completely," Wyenandt said.
With the same options last year, farmers "still had a major problem," he said. "We know 100 percent of the acreage will be affected, but we're not sure how much basil will be lost."
Home growers, without access to commercial fungicide, are "at the mercy" of the disease, Wyenandt said.
The fungus is not toxic to humans, but it renders plants unattractive, unappetizing - and unmarketable. Growers may harvest their crop early as a precaution.
"The best way to stop the disease is to plant varieties of basil that are resistant to it," Wyenandt said. Those species "are not as popular as the traditional varieties with the large leaf."
New Jersey, which ranks third in the nation for fresh herb production, had its 500 acres of basil hit hard last year. Pennsylvania, with only a few dozen acres of the herb, was minimally affected.
"It's not a major concern," said Bill Troxell, executive secretary of the Pennsylvania Vegetable Growers Association. Seventy farms grow "less than an acre of herbs" each.
About 11,000 acres of basil are planted in the United States, and all of it is at risk. The disease has been found in 17 states.
"People see bountiful crops at affordable prices, but behind the scenes, growers struggle with this kind of situation," said Peter Furey, executive director of the New Jersey Farm Bureau, which represents most of the state's farmers.
"The same applies with drought or too much water," he said. "Farmers cope with pretty challenging problems."
Basil is especially popular in summer as the main ingredient in Italian pesto, said Lynne Richmond, a spokeswoman for the New Jersey Department of Agriculture.
Downy mildew was first detected in Uganda in 1933, said Meg McGrath, a vegetable pathologist for Cornell University at the Long Island Horticultural Research and Extension Center.
It spread to Europe in the 1940s and Florida in 2007, then migrated up the East Coast to Canada and to parts of the Midwest and California.
"We assume it came in from seed from Europe," McGrath said. "We live in a global environment where produce, plants, and seeds are shipped all over the world."
Once here, the spores were "aerially dispersed," she said. "It's not something you can easily prevent."
The basil fungus was first reported in the Garden State in 2008, but it gained a strong foothold last year. It "was an ideal year weather-wise with all the regular rain," Wyenandt said.
The first case of downy mildew last year was reported July 22, he said. This year, it arrived two weeks earlier.
The basil-specific disease is a parasite that feeds off the plant, eventually killing it. A similar fungus called powdery mildew affects pumpkins, watermelons, gourds, and cantaloupes.
"It's unlikely we will escape," Wyenandt said.
Contact staff writer Edward Colimore at 856-779-3833 or firstname.lastname@example.org.