According to the The South Carolina Grower, downy mildew disease was found Wednesday in one watermelon field in Bamberg County, South Carolina.
Justin Ballew, Clemson Extension commercial horticulture agent, said all growers should immediately spray watermelon with Ranman, Revus, or Gavel to protect their crops from the disease. In addition to direct yield loss, loss of vine cover can expose fruit to sunburn. Growers who find downy mildew in a field should apply Orondis Ultra or Orondis Opti in a weekly rotation with Ranman or Gavel.
According to a previous UGA news release, the downy mildew pathogen thrives in wet, humid conditions and needs moisture on the surface of the plant for successful spore germination and further infection.
Cucurbit crops — like cucumbers, melons, squashes and pumpkins — are susceptible to the disease.