The Minnesota Department of Agriculture has discovered the state's first case of basil downy mildew, a fungus that affects basil plants.
The fungus was discovered by a gardener in the state about a week and-a-half ago and confirmed by state Department of Agriculture tests, said Geir Friisoe, the agency's plant protection division director.
"Initially, the symptoms that one would see is just a yellowing between the veins on the leaves and then later you get more of the characteristic downy mildew on the undersides of the leaves," Friisoe told MPR's All Things Considered on Wednesday. "You can get some black speckling, which is actually the spores that are being formed."
The fungus poses no health risks, although it makes basil unpalatable, Friisoe said.
Gardeners can limit their chances of encountering the disease by buying seeds from reputable dealers and avoiding starter plants that are showing symptoms, he said.
The fungus can develop in either commercial or home gardens, and is spread by airborne fungi spores or infected seeds.
Friisoe said the disease could initially be "devastating" to basil plants in the state, although resistant varieties are likely only a few years away.