| Pruning
strategies to alleviate overcrowding in higher density citrus orchards. |
| Joubert, F.
J.,Plessis, M. H. du,Stassen, P. J. C. |
| ARC,
Institute for Tropical and Subtropical Crops, Private Bag X11208,
Nelspruit, 1200, South Africa. |
| In this study
different pruning methods were applied to higher density orange (cv.
Navel), grapefruit (cv. Star Ruby) and orange (cv. Valencia) orchards
(in South Africa, in 1996-99), which had become overcrowded five to six
years after planting. A progressive decline in yield and fruit size was
experienced with these orchards. Response to the different pruning
actions, as well as yield variation and fruit size was assessed over
three successive seasons. Corrective (severe) pruning and hedging
resulted in a significant reduction in yield in the 1st year after
pruning, but with an increase in fruit size. However, yield and fruit
size improved substantially in the 2nd and 3rd year after the severe
pruning. Light hedging as a maintenance pruning action was effective in
restricting tree size without adversely affecting yield. Alternate
bearing was substantially reduced by annual pruning. By creating a
slanted, 20 deg angle canopy with mechanical hedging and selective
pruning, a greater portion of fruit is borne within reach from the
ground. The narrower tree tops also improve light penetration. Regrowth
developed more evenly over the total leaf area at this slanted angle.
Mechanical hedging alone proved to be unsuccessful, due to the
development of a too dense outer-canopy. All pruning methods eventually
resulted in an increased yield and improved fruit quality compared to
the unpruned control. A combination of mechanical hedging (10 deg to 20
deg ) and selective pruning (2-3 times/year), is the recommended
procedure for alleviating overcrowding in higher density orchards. |
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