Cercospora leaf spot disease, the most damaging disease on beet greens and bunch beets, can be managed just as equally with either conventional or organic fungicides, according to The South Carolina Grower, Clemson plant pathologist Tony Keinath.
Based on previous research in New York with processing beets, Keinath evaluated the best conventional program – Tilt alternated with Quadris – and the best organic program – Cueva + Double Nickel – on six beet cultivars grown and harvested for greens in spring 2021.
“The results with fungicides were clear cut but not that encouraging overall. The good news is that both programs reduced the severity of Cercospora leaf spot compared to the water-sprayed control. The not-so-good news is that spraying did not increase the number, weight or percentage of healthy leaves,” Keinath said. “Fungicides worked the same across the six beet cultivars tested.”
Quadris, when applied to beets, must be rotated 1:1 with another fungicide. Tilt was chosen for this trial instead of the cheaper Monsoon (generic tebuconazole). Lab fungicide sensitivity testing of SC Cercospora isolates showed they are more likely to be sensitive to Tilt than Monsoon.
“The question remains whether spraying beets for Cercospora leaf spot is worth the cost. From a strictly economic perspective, the answer, at this point, is not really. The trial is being repeated in spring 2022 to verify the results from 2021,” Keinath said.
