Rates are based on typical full size trees. When treating younger blocks with smaller tree size, adjust the rate per acre downward. Ethephon is applied 8-14 days prior to anticipated harvest. The time required to achieve adequate loosening is a function of ethephon rate and temperature. Conversely, if temperatures are expected to be below normal, rates slightly higher than normal may be used.
Questions always arise about tank mixing ethephon.
While there is no research data regarding tank-mixing ethephon, according to experience there appears to be no problem tank mixing ethephon with the fungicides and insecticides commonly used at this time. However, it is possible that materials in the tank may act as a buffer to the ethephon thereby causing some loss in activity. This could be overcome by acidifying the tank mixture prior to the ethephon being added. Do not tank mix with foliar nutrients or compounds such as crack inhibitors, bird repellents, etc. Avoid the use of surfactants unless prior experience has indicated their effect on the ethephon.