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Title Howard walnut trees can be brought into bearing without annual pruning
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In traditionally managed Howard walnut orchards, trees are pruned annually during the orchard development phase, an expensive operation in terms of labor and prunings disposal costs. Our observations and some prior research by others had suggested that pruning may not be necessary in walnut. In a trial of pruned and unpruned hedgerow trees over 8 years, beginning a year after planting, we documented canopy growth, tree height, yield and nut quality characteristics and also the effects of fruit removal. Pruning altered canopy shape but did not lead to increases in canopy development, yield or nut quality. Although fruit removal stimulated more vegetative growth in both the pruned and unpruned treatments, fruit removal did not result in an increase in midday canopy photosynthetically active radiation interception or cumulative yield when fruit removal was stopped after year 4. After 8 years, there were no significant differences in tree height, nut quality or cumulative yield among any of the treatments, which suggests that not pruning young Howard orchards could provide a net benefit to growers.

Lampinen, Bruce D
Integrated Orchard Management Walnut and Almond Specialist
Integrated Orchard Management with an emphasis on walnuts and almonds
Edstrom, John Paul
Farm Advisor emeritus
Metcalf, Samuel G. : S.G. Metcalf is Staff Research Associate in the Department of Plant Sciences at UC Davis
Stewart, William
Staff Research Associate I
Negron, Claudia M. : C.M. Negron was Graduate Student in the Department of Plant Sciences at UC Davis
Contador, M. Loreto : M.L. Contador is Assistant Specialist in the Department of Plant Sciences at UC Davis.
Publication Date Apr 1, 2015
Date Added Jun 24, 2015
Copyright © The Regents of the University of California
Copyright Year 2015

After 8 years, tree height, nut quality and cumulative yield were not significantly different among pruned and unpruned trees in a developing orchard.

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