New Basil Bred to Get the Upper Hand on Downy Mildew

New Basil Bred to Get the Upper Hand on Downy Mildew

Test field of downy mildew-resistant basil

Herb grower and marketer Charlie Coiner looks over a test field of downy mildew-resistant basil plants. Photo courtesy of Hayfield Farm

Basil is a widely used, versatile herb with an ever-growing fan base around the globe. One foe, however — downy mildew — poses an increasing threat to the herb’s availability. Downy mildew of basil is a destructive pathogen that develops on lower leaf surfaces, all but rendering complete crop loss for growers as what’s left is likely unmarketable and inedible. Three herb industry stakeholders are seeking to change the game and introduce downy mildew-resistant basil varieties to the marketplace.

Jim Simon, a Professor of plant biology at Rutgers University; Charlie Coiner, an herb industry grower and marketer; and Ed Van Drunen, retired President at Van Drunen Farms in Momence, IL, have been leading the charge to achieve a commercially viable downy mildew-resistant variety to offer growers.


“What we were aiming to develop is a plant that will sufficiently grow without concern about symptomology during the growing and harvest season and as such we are talking about degrees of tolerance, not only resistance,” Simon stated.

According to a report from Cornell University, downy mildew of basil is confirmed in both field- and greenhouse-grown crops (as well as home gardens) in many states including Florida, Georgia, Indiana, Illinois, North Carolina, Pennsylvania, New Jersey, New York, Massachusetts, Kansas, and Missouri.

Coiner points to telling statistics as an indication of how the disease has impacted basil production. “Five years ago, 28 farmers in New Jersey listed themselves as commercial producers of basil. But in 2016, only two did.”

The trio applied for a patent for the downy mildew-resistant varieties, and the seeds are now cleaned, tested, packaged, and commercially available through VDF Specialty Seeds.

Simon noted team effort was a key ingredient to the R&D success behind the seven-year-long project, which produced 12 lines of basil that show downy mildew resistance. “It was mostly done at Rutgers, but also with collaboration from Cornell University, the University of Florida, the University of Massachusetts, and many commercial growers all over the country.”

Selection of the final four lines being released were decided using a participatory approach with commercial basil farmers in the U.S. and European Union. “The lines chosen to commercialize are similar because they all go back to the cross that established the downy mildew resistance,” Coiner says.  “Since then, the breeding has tried to select for some diversity for the people that grow basil. For example, greenhouse growers asked for a more cup-shaped leaf. Field growers wanted big plants that produce a lot of leaves. Some wanted resistance to Fusarium.”