Note: Timings listed are effective, but not all may be required for disease control. Timings used will depend upon orchard history of disease and weather conditions each year.
|Disease||Catkin emergence||Terminal bud break||7–10 day intervals||Apr.||May||June||July||Aug.
(3-wk before hull split)
(20–30% hull split)
|Walnut blight3, 4, 5||25||3||3||3||2||1||0||0||0||0||0|
|Rating: 3 = most effective, 2 = moderately effective, 1 = least effective, and 0 = ineffective|
|1 Make the first application when the size of the expanding leaves is about half of its final size. This first application stage is critical.|
|2 Timing for kernel mold is based on a mixture rotation of Merivon (FRAC group 7/11) and Teb (FRAC group 3) followed by Rhyme (FRAC group 3) at the timings indicated. This mixture rotation is ‘3' based on the ratings in the efficacy table above.|
|3 A temperature-leaf wetness model (e.g., Xanthocast) is available for determining optimum timing of bactericide applications.|
|4 Late spring rains are less conducive to disease, provided bloom is not delayed by low chilling.|
|5 Male and female flowers are susceptible beginning with their emergence, depending on wetness and temperatures conducive to disease development.|
Acknowledgment: Adaskaveg et al., 2022. Fungicides, Bactericides, Biocontrols, and Natural Products for Deciduous Tree Fruit and Nut, Citrus, Strawberry, and Vine Crops in California. (PDF)