Absorption and persistence of 2,4,5-TP in Packham's Triumph pear trees

Fruit set of the pear cultivar Packham's Triumph is significantly improved by a post-harvest application of 2-(2,4,5-trichlorophenoxy) propionic acid (2,4,5-TP), implying a persistence long enough to prevent fruitlet abscission the following spring. Since no literature regarding the persistence of 2,4,5-TP in higher plants could be found, it was decided to study its persistence in Packham's Triumph pear tissue following postharvest applications. Residual 2,4,5-TP in the tissues was determined by electron capture gas chromatography. It was found that 2,4,5-TP did not persist in detectable levels in the tissues of potted saplings until spring. However, significant amounts were found in buds of full-grown trees until bud break, as well as in leaves and fruitlets developing from these buds