ISHS Acta Horticulturae 998: EUFRIN Thinning Working Group Symposia
FRUIT THINNING IN POME- AND STONE-FRUIT: STATE OF THE ART |
| Authors: | D. Greene, G. Costa |
| Keywords: | thinning methods, new formulates, fruit quality, modeling |
| DOI: | 10.17660/ActaHortic.2013.998.10 |
| Abstract:
Fruit thinning is an activity that is normally done over a relatively wide time period from bloom until fruit grow to above 18 mm in diameter. Manual, chemical and mechanical methods are used, alone or in combination, but the method chosen depends upon species, climatic conditions and the historic reliability of the proposed method. Pome-fruit are most frequently thinned using chemical methods whereas stone-fruit are routinely thinned manually. The chemicals most frequently chosen to thin pome-fruit, and apple in particular, at bloom are 2-chlorophosphonic acid (ethephon), ammonium thiosulfate (ATS), oil and lime sulfur while the auxins naphthaleneacetic acid (NAA) and naphthaleneacetamide (NAAm), the cytokinin 6-benzyladenine (6-BA) and, in some locations, the insecticide carbaryl are applied at the fruitlet stage. Stone-fruit and in particular peach are most frequently thinned at bloom using bloom thinners (caustic compounds, dormancy breaking agents, oils) and fruitlet thinners are infrequently used. In this category, ethephon has been tested but it is not been shown to be very reliable and there are undesirable side effects that do not allow this formulation be used as a routine practice. Recently mechanical thinning has emerged as potential viable option for thinning both pome and stone fruit using the Darwin and Baum machines. The precision and predictability of thinners and thinner responses have been significantly improved using newly developed modeling systems that monitor fruit growth or estimate the carbon balance within a tree. In addition, new molecules have emerged and are under evaluation that shows real promise as new chemical thinners. These include the photosynthesis inhibitor metamitron (Brevis) and two naturally occurring compounds, abscisic acid (ABA) and 1-aminocyclopropane-1-carboxylic acid (ACC). | |
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