Citrus Pruning: How and What? by Cindy Fake, County Extension (UCCE), California

1. Pruning Citrus
How and What
Cindy Fake
University of California Cooperative Extension,
Placer & Nevada Counties
January 2012

2. How to Prune…
• Carefully!
• Citrus bark is thin and
easily damaged so avoid
nicks
• Make pruning cuts with the
blade toward the tree
• Cut cleanly and avoid
damaging remaining
branch
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3. How to Prune…
• Do not cut branches flush
with trunk
• Preserve branch collar =
ridge in bark around base
of branch
• Branch collar contains cells
that make woundwood which
grows over a pruning cut
• Branch collar also makes compounds to
defend tree against decay
• Do not paint or tar wounds
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4. How to Prune…
• When cut too closely,
wound includes trunk wood
• Do not leave long stubs –+/-
1 cm above branch collar is
sufficient
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5. How to Prune…
• Citrus has brittle wood
• Use a three-cut system for
branches larger than 2.5 cm
• Prevents bark tearing or
damage to remaining branch
• 1st cut: 30 cm from branch union
• Cut 1/3 to ½ way through the branch from underneath
(undercut)
• 2nd : A few cm up, cut from above, removing the
branch. Make the final cut just above branch collar
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6. How to Prune…
• If previously shaded branches are
exposed to sun, protect them from
sunburn
• Sunburn causes bark cracking and
cankers, which may kill the tree
• Paint exposed branches with
whitewash or 1:1 mixture of
interior latex paint and water
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7. What to Prune?
• Best is to prune branches less than
5 cm in diameter
• Why? …because they are mostly
living tissue and can protect
themselves against decay better
than larger branches
• This means pruning regularly, not
leaving it until you need to take
out large branches
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8. Types of Pruning: Topping
• Top young trees at planting,
esp. if they are tall and
spindly
• Promotes side shoots which
develop into a lower, fuller
canopy
• The shorter the tree, the
easier and more cost
effective the harvest
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9. Types of Pruning: Shaping young trees
• Prune downward growing
shoots to allow upward
growing buds to become
dominant
• Cutting the shoot just above
an axillary bud pointing
upward will redirect growth
upward
• Helps shape the tree for
optimal future production
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10. Maintenance Pruning
• Remove discolored, damaged,
or dead wood from trees as
necessary through the year
• Remove crossing branches or
branches that shade out
lower branches
• Remove branches infected with
citrus blast (Pseudomonas
syringae) when weather warms in
the spring
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11. Suckering
• Remove shoots below the bud
union as soon as they appear
• They are growing from the
rootstock and will not be
productive
• For Trifoliate rootstocks,
(Poncirus trifoliata) the rootstock
thorns can be a hazard to workers
and may damage fruit
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12. Removing Watershoots
• Long, thick, very vigorous
branches = water sprouts or
gourmands
• Grow very rapidly, using large
amounts of nutrients and water
• Typically remain vegetative for
multiple years
• Produce poor quality, large, rough
fruit, with dry segments
• Do not contribute to production, so
should be removed at the base.
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13. Reducing Tree Height
• Without regular pruning, fruit
production is on top of the tree
• Increases harvest time and costs
• Cutting major branches back to the
base is too hard on tree
• Only ¼ to 1/3 of tree height should
be reduced at a time
• Leave a few branches with good
foliage to photosynthesize and draw
water through the plant
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14. Canopy thinning
• Sunlight develops flavors and sugars
in the fruit
• A dense canopy prevents
sunlight from reaching fruit
• Thin canopy every 2-3 years
• Should see dappled sunlight beneath
tree at midday
• Thin out center branches
before they get large => increase
fruiting wood in the center
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15. Canopy thinning
• To facilitate thinning,
divide trees into
quadrants based on
scaffold or primary
branches
• Assess what is best in
each quadrant
• Prune one section at a
time
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16. Canopy rejuvenation
• This tree has too much trunk
and a very thin canopy, which
means yields are low
• Canopy needs to be brought
down so fruit is accessible
• Large branches with few
leaves and low bearing
potential need to be removed
to stimulate new growth in
center
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17. Skirt Pruning
• Branches that hang to the ground
• “Skirts” impede weeding, and fertilizer or
compost application
• Allow ants to access trees
• With heavy fruit loads, branches bend and
fruit touches the ground
• Fruit may be contaminated by soil
borne pathogens
• May cause plant disease, e.g. Brown rot
• Also potential food safety risk
• Skirt trees 50-75 cm above ground
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18. Pruning for Pest Management
• Soft-bodied, sucking insect pests
such as scale and mealy bugs thrive
in dense canopies
• They like high humidity and little
air movement
• The canopy protects pests from
predators and parasitoids
• Thinning the canopy often reduces
pest populations to the point that
insecticide sprays are unnecessary.
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19. Pruning for Pest Management: Citrus Blast
• Pseudomonas syringae bacteria
cause disease
• Common where Satsumas grow
• Usually starts at the base of the
petiole on small shoot
• Can move into larger branches
• Can cause cankers which kill limbs
• Prune out damage each spring to
remove as much of the infection as
possible
• Cut 15 cm below visible infection
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20. What to do with Prunings?
• Significant amount of green
material
• Could be returned to soil to the
benefit of trees
• Difficult to leave prunings lie in
orchard…hazard
• Burning loses all good benefits
• If prunings are not from diseased trees,
– Compost with cow or other manures
– Use compost as mulch along tree rows, under trees
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21. How and what?
Thank you!
Cindy Fake
University of California Cooperative
Extension, Placer & Nevada Counties
January 2012
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