Downy mildew disease was found on watermelon this week in two South Carolina counties – Allendale and Barnwell – according to The South Carolina Grower. This is especially concerning, since it reduces sugar content once 25% are infected.
All watermelons should be sprayed with a fungicide effective against downy mildew. Gavel, Ranman and Elumin are the least expensive fungicide choices. Producers should apply a downy-mildew specific fungicide this week, a protectant, such as chlorothalonil or mancozeb, next week and repeat this sequence until one week before the final harvest.
Downy mildew can destroy plant foliage and cause the leaves to curl and die. Without healthy leaves and vines, a plant is vulnerable to blisters and sunscald during hot summer days.