Proper Pruning Techniques for Disease Management Presented by Bess Bronstein, Horticultural Consultant & ISA Certiﬁed Arborist Plant Health Safety

1/2/19

Pruning Objectives Proper Pruning Techniques for Disease Management presented by Bess Bronstein, Horticultural Consultant & ISA Certiﬁed Arborist Plant Health Safety

Direct Growth Increase Flowers & Fruit Aesthetics

Remember-

Plants have a genetically predetermined size. Pruning cant solve all problems. So, plant the You can try to control right plant in the right way in the right place. the size or shape, but….....

genetics will win.

1 1/2/19

One year old Stem & Buds Two years old Epicormic Growth Three years old Internode § stem area Growth from dormant buds, either between latent or adventitious. These nodes branches are weakly attached.

Bud scale scars § indicates yearly growth and tree vigor Node § buds, leaves and branches arise here Latent bud § inactive lateral buds at nodes Adventitious bud Watersprouts § found in unexpected areas (roots, stems) Suckers

One year old Apical Dominance Stem & Buds Two years old Three years old

Apical (terminal) bud Internode § found at tips of branches § stem area between Axillary (lateral) bud nodes § found along branches below tips Bud scale scars § indicates yearly growth and tree vigor Node § buds, leaves and branches The apical (terminal) bud When apical dominance is broken arise here contains the apical by injury (storms, animals, etc.) or Latent bud meristem, which contains pruning, lateral and dormant buds § inactive lateral buds at nodes plant hormones called ﬁght to become the new terminal Adventitious bud auxins that inhibit growth of leader. § found in unexpected areas (roots, stems) lateral buds.

2 1/2/19

Woody Plant Tissues: Xylem Woody Plant Tissues: Vascular Cambium

Sapwood Heartwood Bark Heartwood Phloem (active) • provides Cork structural cambium backbone Cork Sapwood • conducts water and nutrients from roots This is a secondary (lateral) meristem that allows for throughout increase in xylem and phloem tissues, as well as cambium the tree cells. The result is increased stem and trunk diameter. Vascular Pruning Trees cambium

Woody Plant Tissues: Bark (Inner) Woody Plant Tissues: Bark (Outer)

Sapwood Heartwood Bark Sapwood Heartwood Bark Cork Phloem (active) Phloem (active) Phloem (active) • protection Cork • conducts food Cork cambium from the cambium Cork cambium Cork leaves Cork • cambium cells throughout present in the plant some species and increases cork

Vascular Vascular Pruning Trees cambium Pruning Trees cambium

3 1/2/19

Annual Growth Rings Vascular Rays

Earlywood (Springwood) Latewood (Summerwood) • First new wood in spring • Growth later in summer Vascular rays transport sugars and other compounds • Large cells with thin cell • Small cells with thicker cell radially through vascular tissues, store starch, and assist in walls walls restricting decay in wood tissue. • Light in color • Dark in color

CODIT: compartmentalization of decay in trees

• plants can limit, or wall off, decay that sets in after wounding • plants dont HEAL, they chemically SEAL off damage • CODIT works best on young wood (1-3 yrs.)

• species vary in successful compartmentalization Photo courtesy of Shigo and Trees, Associates • 4 walls form to varying degrees of success Wall 2: pre-existing defense of cells formed at the annual growth rings to Wall 1: prevents the spread of slow spread of decay toward the center decay up and down the branch of the tree or trunk by plugging the vertical cells as a reaction to wounding Wall 3: pre-existing defense of ray’ (weakest wall) cells that slow spread of decay around the tree

4 1/2/19

Tree Structure

Trunk

Wall 4: a ‘barrier zone’ Crown formed as a reaction to • leaders wounding that consists • scaffold branches of new strong dense • lateral branches wood (strongest wall) • spur shoots • twigs

Epicormics • suckers • watersprouts

Branch Wood and Trunk Wood Branch Collar & Branch Bark Ridge

Branch Bark Ridge

Branch Branch Collar Collar

Branch collar with no visible branch bark ridge Photos by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida

Photos by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida

5 1/2/19

Types of Branch Attachments Codominants & Included Bark

• strong attachments have smaller branches (branch wood) secured in larger branches or trunks (trunk wood)

• trunk wood forms a branch collar around the branch wood, and a branch bark ridge is often visible

• codominant stems are poorly attached

• included bark forms both in codominant and narrow angled attachments Photo by Edward F. Gilman, Professor, Environmental HorBculture Department, IFAS, University of Florida

Illustrations by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida

Codominants with included bark (and decay) Pruning Cuts

Heading

Reduction

Removal

Photo by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida

6 1/2/19

Pruning Cuts Pruning Cut: Heading Heading Reduction Removal (Thinning) • localized response • ‘hydra effect • leaves stubs • cut to a node (selective heading) Photo by Edward F. Gilman, Professor, Environmental Horticulture Department, • shearing IFAS, University of Florida (non-selective heading) • topping (non-selective heading)

http://www.aislinnadams.com/tag/illustration-botanical/ http://www.sunset.com/garden/garden-basics/basic-pruning-cuts Illustrations: VanDerZanden, Ann Marie and Diane Nelson. 2004. Pruning Ornamental Shrubs, PM 1958, Iowa State University Extension

Illustration: VanDerZanden, Ann Marie and Diane Nelson. 2004. Pruning Ornamental Shrubs, PM 1958, Iowa State University Extension

7 1/2/19

Shearing Disease Problems of Commonly Sheared Plants

• boxwood (Buxus spp.) • use on plants with small § boxwood blight leaves that are tough § boxwood canker enough to take it • photinia (Photinia x fraseri) • some large leaf plants OK § entomosporium fungal leaf spot § powdery mildew

• formal look Photo by Jay W. Pscheidt, 1996. • non-selective heading, can lead to increased • pyracantha (Pyracantha spp.) plant stress and increase § bacterial blights in pest/disease problems • junipers (Juniperus spp.) § juniper phomopsis fungal blight

Topping Pruning Cut: Reduction

• Selective removal of branches or partsPruning of branches Cut Types • cuts through several to decrease heightPruning and/or Cut spread Types of a tree years old wood HEADING CUT ● THINNING HEADINGCUT ● REDUCTION CUT ● THINNING CUT CUT ● REDUCTION CUT • ugly • doesn’t work to reduce height; plant responds with new, poorly attached stems • expensive to maintain • unhealthy; opens tree to decay

8 1/2/19

Pruning Cut Types Reduction Cut Heading or Reduction Cut? HEADING CUT ● THINNING CUT ● REDUCTION CUT • cut the branch to a lateral stem large enough to assume the role of Heading Reduction terminal leader • at least to ½ the diameter of the removed stem Cut here • if the lateral stem or Cut to a node branch is too small Lateral of a diameter, branch epicormic shoots will remains develop Illustrations by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida

Crown Reduction Oops!

• Selective removal of branches or parts of branches to decrease height and/or spread of a tree

Pollarding?

9 1/2/19

Pruning Cut: Removal

• cut to branchs point of origin • preserves apical dominance and looks natural • cut outside of branch collar and avoid tearing plant tissue • no ﬂush cuts Excessive sprouting

Photo by Edward F. Gilman, Professor, Environmental HorBculture Department, IFAS, University of Florida http://www.sunset.com/garden/garden-basics/basic- pruning-cuts

How to Make a Removal Cut

Cut #2

Cut #3 • cut just outside the branch collar Cut #1 Branch bark • the branch collar is ridge kept intact

Branch collar

Photo by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida

Photo by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of • locate branch collar (use branch bark ridge for guidance) Florida

10 1/2/19

Callus & Woundwood Crown Cleaning

• Removal of dead, diseased, broken, and rubbing branches • symmetrical formation • Reduces the risk of branch failure indicates proper cut

• asymmetrical formation indicates cut into trunk wood

Pruning Trees

Thinning Thinning

• Selective removal and reduction of live branches to • Useful renovation technique for previously reduce density in the crown of a tree or in a shrub over-pruned plants • Increase light and air • Reduce risk of tree branch failure in wind and storms

BEFORE AFTER

• cut smaller • open and laterals off natural look main stems

Photos by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida

11 1/2/19

Crown Thinning

• Selective removal and reduction of live branches to reduce density in the crown Good Thinning • Increase light and air in canopy • Reduce risk of branch failure in wind and storms

Bad Thinning (Lions-tailing)

Pruning Trees

Excessive end weight Excessive end weight Response to Over-thinning Unbalanced Canopy after after

before before

Large pruning cut

12 1/2/19 Woody Plant Anatomy

Branch Unions Structural Pruning

• Improve structural strength • Reduce maintenance costs over time

• Increase life of the tree lateral branch

RemoveIncluded defects Bark such as • codominant stems • weak branch attachments • large lower limbs Photos by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida

Early structural pruning means less need for maintenance of larger, mature trees: • fewer branches mean less pruning • well spaced branches mean easier access • pruning can be done faster Pruning Trees Photos by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida

13 1/2/19

5 Steps for Pruning Young Trees Before Pruning After Pruning

STEP 1: Remove dead, dying, diseased, damaged and broken branches. STEP 2: Select and establish a central leader. STEP 3: Select and establish the lowest permanent branch. STEP 4: Select and establish scaffold branches. STEP 5: Select temporary branches below the lowest permanent branch.

Photos by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida

2 Years Later

Photo by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida Pruning Trees Photo by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida

14 1/2/19

Pruning Cycle & Pruning Dose

Pruning cycle: • the interval between each pruning Pruning dose: • the amount of live tissue removed at one pruning

Pruning cycle more than 3-5 years = higher pruning dose Pruning cycle every 1-2 years = smaller pruning dose

Pruning Trees Photo by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida

Shrubs Cane Growing Shrubs

• renew growth by sending up canes • very tough- can take hard pruning • remove - of old, puny canes to the base • can renovate by coppicing

15 1/2/19

3-5 Year Renovation Radical Renovation

Illustrations: VanDerZanden, Ann Marie and Diane Nelson. 2004. Pruning Ornamental Shrubs, PM 1958, Iowa State University Extension

Radical Renovation Mounds or Forms

• grow in deﬁned shape or form • mostly thinning cuts • reach in and thin out unruly or too tall branches • renovate by thinning (reduction & removal cuts)

16 1/2/19

Tree-likes

• form resembles a miniature tree • needs least amount of pruning • thinning cuts only (removal, some reduction) • can be arborized

Tree-likes Rhododendrons

17 1/2/19

Hedges

Is radical renovation of • small leaved plants rhododendrons work best a good thing? • usually a formal look • taper so the top is narrower than the base

Hedge Renovation Hedge Renovation

18 1/2/19

Hedge Renovation Conifers

Timing Timing

Winter Spring Summer Fall

19 1/2/19

The bottom line on pruning- Don’t get lost-

• remove the 4 ds ﬁrst- dead, damaged, diseased and deranged • with ornamentals, do mostly thinning cuts to retain natural form and structure • if you cant identify the plant, dont over prune • know WHY you are making each cut

Have fun!