Ethephon for fruit thinning of Imperial and Beauty of Glen Retreat mandarins in the Central Burnett district, Queensland

Abstract

Ethephon was tested as a fruit thinning agent for mandarins in three experiments in the Central Burnett district of Queensland. Ethephon at concentrations between 200 and 300 ppm successfully thinned fruit on the Glen Retreat cultivar. However, the excessive leaf fall that occurred at 300 ppm indicates some risk. Therefore, further experiments are desirable to confirm its commercial potential. The Imperial cultivar was thinned by ethephon at concentrations within a range of 200 ppm to 500 ppm without excessive leaf fall. A concentration of 250 ppm is suggested for commercial use. Ethephon was most effective when applied before the completion of the natural period of fruit drop in November/December.