By Mongi Zekri
For maximum efficiency of a grove, it is essential that every location is occupied by a tree and that every tree is healthy. Prompt replacement of dead and declining trees means higher average long-term returns from the grove. If the declining trees remain in the grove, they keep getting weaker and yield less fruit each year. Therefore, the potential production capacity for the grove keeps declining even though production costs remain the same. It is very important to remove and replace such trees once it is clear that they are declining and not profitable.
The reason for the decline should be determined, and the condition should be corrected so that the replacement tree does not suffer the same fate. Replanting in a mature grove seems justified only when a minimum of 8 feet between canopy driplines, not from trunk-to-trunk, is available for canopy development of the new trees.
Caring for young citrus trees is not an easy task. Resets should be watered, protected, fertilized and weeded regularly. Because of their frequent flushing cycles, young trees are more sensitive and more attractive to pests than mature trees. Special care is needed to control the citrus psyllid and citrus leafminer. A rigorous program including systemic (imidacloprid and thiamethoxam) and contact pesticides is recommended.
Resets often present an even greater problem because trees are usually scattered throughout the grove. Scattered resets frequently have serious weed problems since removal of the previous tree allows the area to receive more sunlight and provides more favorable conditions for weed growth. Keep weeds under control during the establishment period of the reset because weeds compete with young citrus trees for moisture and nutrients.
Weed control around a reset site should be considered at pre-plant, early post-plant and after the tree is established. If residual herbicides are used, they should be applied in greatly reduced rates and well in advance of planting so that harmful residues do not remain which might damage the reset. Contact or growth-regulating herbicides are usually preferred since they do not leave residual effects.
If the grove is under a fertigation program, there is no need for special care in terms of nutrition for resets. The use of controlled-release fertilizers for resets may be a better option than making several trips with soluble dry fertilizers to scattered resets throughout large blocks.
Young citrus trees require frequent but moderate water application for survival and proper growth. Drainage is as important as irrigation. Excess water must be removed from the rootzone.
Mongi Zekri is a multi-county University of Florida Institute of Food and Agricultural Sciences Extension citrus agent covering Charlotte, Collier, Glades, Hendry and Lee counties.
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