Propagation and�Nursery Production

Propagation Methods

• Seed
• Results in wide genetic variation
• Still used for rootstocks
• Requires stratification at 2-6^oC for 3 months
• Some apomictic seedlings (arising only from maternal cells within ovary)
• Vegetative (Clonal)
• Identical plants to parent
• Principal method of propagation

• Methods of vegetative propagation:
• Cuttings: young plants separated from mother plant
• Softwood: leafy shoot tips collected in spring or summer & rooted
• Hardwood: leafless, 1-year-old shoots collect in winter & rooted
• Division: young plants remain attached to mother plant until they form roots
• Mound or stool layering
• Trench layering
• Micropropagation (in vitro):
• Used mainly for certain difficult to root rootstocks

Propagation by Division

• Mounding (stooling)
• 1-year-old rooted plants planted vertically in spring & left unpruned for 1 year
• Shoots cut back following spring & soil or sawdust mounded around shoot bases
• Layering (in trenches with stone fruits)
• 1-year-old rooted plants planted obilquely & left unpruned for 1 year
• Shoots bent & secured flat to ground following spring & soil or sawdust mounded around shoot bases

Mound (Stool) Layering

Rootstock

Mounding

sawdust

“Mother”

rootstock

“Daughter”

rootstocks

Trench Layering

“Mother”

rootstock

“Daughter”

rootstocks

Layering with

soil or sawdust

“Mother” Rootstocks

Mounded

daughter

rootstocks

Dormant

daughter

rootstocks

Roots of

daughter

rootstocks

Micropropagation

• Shoot tips cultured in sterile medium containing mineral salts, carbohydrate & growth hormone (cytokinin)
• Further multiplication from new shoots
• Poor orchard performance:
• Delayed cropping
• Increased root suckers & burr knots

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Producing Nursery Trees

• 1-year-old trees
• Budding on established rootstocks, planted as “liners” in early spring
• Trees “lifted” & either sold immediately for fall planting or stored for spring planting
• “Snip” trees
• Rootstocks lined in early spring contain a dormant (“sleepy”) bud
• Single stem (“whip”) cut following spring at 50-80 cm above ground & only top bud is allowed to grow, which forms laterals

• Interstem trees
• 2 year cycle to bud interstem one year & scion next year
• Used when unfavorable soil conditions require a certain rootstock:
• M.9 interstem for dwarfing on a MM.111 rootstock for woolly apple aphid tolerance
• Early cropping usually better on snip & interstem trees
• More lateral branches  higher early yields
• More expensive trees to product

“T” Budding

Inserting & tying

Cutting rootstock

Cutting scion T bud

Chip Budding

Cutting rootstock

Cutting scion chip bud

Tying bud

Chip Budding

Tree Harvesters

Ideal root

development

“Feathered”

trees

Lateral Shoots�‘Jonagold’/M.9

Within row tree spacing (cm)

Wertheim et al., 1989

Lateral Shoots�‘Red Boskoop’/M.9

Wertheim et al., 1989

Promalin™

GA₄ (25%)

GA₇ (25%)

Gibberellins (promote cell elongation)

Cytokinins (promote cell division)

6-benzylamino purine (50%)

(benzyladenine, BA)

Chemical Branching

0

50

100

300

600

ppm BA sprayed weekly (8X)

“Snip” Tree

“Whip” cut in spring

after 1-year growth

on rootstock

Bundling

rootstocks

Bridge Grafting

Inarch Grafting