Using combinations of GA3, GA4+7, AVG and Pro-hexadione-Ca to improve fruit set on Abate Fetel and Forelle pears

Maintaining constant high yields in ‘Abate Fetel’ and ‘Forelle’ orchards in South Africa is challenging.  One way of improving productivity in these orchards is to increase fruit set.  Various protocols to improve fruit set are used by South African producers without knowing whether these indeed improve set.  Different combinations of plant growth regulators including gibberellic acid (GA₃), gibberellins 4+7 (GA₄₊₇), (GA₄₊₇ + 6-benzyladenine (6-BA)), aminoethoxyvinylglycine (AVG) and prohexadione-calcium (P-Ca) in combination with trunk girdling were applied during flowering to determine the best fruit set strategy.  All applied growth regulators improved fruit set relative to an untreated control over two consecutive seasons but GA₃ and P-Ca reduced return bloom and AVG resulted in smaller fruit size relative to the other treatments.