Optimising leaf defoliation in young trees

Nurserymen are concerned that natural leaf fall on field-grown trees is occurring later each year, due to milder autumns. As such, the period in which field-grown trees can be lifted is becoming restricted, and some nurseries are being forced into lifting trees to meet orders whilst the foliage is still attached. Chemical defoliants are available to nurserymen, but these need to be applied with care to promote a strong enough abscission response, yet avoid damaging the crop. Even so, responses vary and the extent of leaf abscission can be unpredictable. One of the main products – ‘Leaf Fall’ encourages abscission but does not directly induce leaf fall per se. This has the advantage in that leaves are not killed on the tree, but it can mean that nurseries still need to hand strip the leaves from the stems. Others nurseries, where labour is more of an issue have no option but to lift and store trees whilst leaves remain attached.

This project aims to optimise the use of existing chemical products, and to explore cultural and alternative techniques that either enhance the effectiveness of these, or provide an alternative mechanism for defoliation.