Regev HBX, a new hybrid fungicide for pecan scab control

Pecan scab is one of the most yield-limiting foliar disease of pecans in the United States. Standard practices to control this disease include selection of resistant cultivars and reliance on fungicide spray programs. However, there are a limited number of fungicides registered for control of pecan scab, and repeated use of these fungicides has imposed selection pressure on the fungal pathogen Venturia effusa for resistance development. Regev HBX™ is a newly registered hybrid fungicide for pecan scab control that contains tea tree oil and the synthetic triazole fungicide difenoconazole. Tea tree oil provides a new and unique mode of activity against both fungal and bacterial plant pathogens, and it has a low risk for resistance development. Five independent field trials were conducted to evaluate Regev HBX for efficacy against pecan scab. Four trials were conducted in 2022 and 2023 in Georgia, and one trial was conducted in Texas in 2021. Across these trials, Regev HBX either alone or combined with other fungicides in spray programs provided effective control of pecan scab similar to, or better than conventional fungicide programs. Tea tree oil alone (Timorex Act) provided significant scab control compared with the untreated controls, indicating that tea tree oil is contributing to pecan scab control provided by Regev HBX.