Effect of polarity on rooting

1
Effect of polarity on rooting

• stem cuttings form shoots at the distal end,
  roots at the proximal end
• auxin always moves from shoot tip to base (no
  matter the stem orientation)

2
Effects of buds and leaves on rooting

• active buds promote rooting, dormant buds have
  no effect
• leaves exert a strong stimulatory influence (both
  carbohydrates and auxin are translocated from
  leaves)

3
Effect of wood type on rooting of woody cuttings

• Seedling (genotype) differences (Norway spruce,
  white pine, red maple)
• lateral shoots usu. better than terminals
• beware plagiotropic growth of laterals
• basal and medial shoot portions are usu. better
  than terminals
• flowering wood is slower than vegetative
• heel cuttings are better for some spp. (quince,
  narrow-leaved evergreen spp)

4
Seasonal timing (when cuttings are taken) can
affect rooting of woody cuttings

• hardwood cuttings with resting buds are best
• softwood cuttings are usu. best from the first
  flush
• narrow-leaved evergreens are best taken from late
  fall to late winter
• broad-leaved evergreens (e.g., olive cuttings
  root best when taken during late spring, poorest
  when taken in midwinter)

5
Cold storage of rooted and unrooted leafy cuttings

• Several days to several weeks (for convenience)
• Temperature near 40o F (4o C) for temperate spp.
• High RH
• Pathogen control

6
Handling field-propagated woody cuttings (after
rooting and lining out)

• bare-root nursery stock - deciduous shrubs, trees
• balled-and-burlapped (B B) stock - broad- or
  narrow-leaved evergreen spp.
• container production - is rapidly replacing field
  production
• easier handling
• improved marketability
• better cultural control
• faster product turnover
• newer alternatives - pot-in-pot, grow bags, etc.

7
Pathogen/pest management in propagation

• Pests (insects, mites, nematodes, weeds)
• Pathogens (fungi, bacteria, viruses)
• Goals
• to keep stock plants and propagules as clean and
  pest-free as possible
• identification, indexing of systemic pathogens

8
Pathogen identification methods

• visual inspection - specific symptoms
• culture indexing - systemic bacteria, fungi
• virus indexing (e.g., indicator cultivars)
• serological tests (e.g., ELISA tests)
• biochemical/molecular methods (e.g., specific
  viral RNA patterns on a gel)

9
Methods of pest/pathogen management in propagation

• preventive measures (e.g., clean stock, use of
  cultivar resistance, scouting)
• integrated pest management (IPM)
• chemical control (e.g., quantity control,
  rotation)
• biological control (the fungus Gliocladim virens
  instead of fungicidal control of Rhizoctonia and
  Pythium damp-off)
• cultural control (e.g., sanitation, healthy stock
  plants, heat pasteurization of propagation medium)

10
Aphid control - a case study of IPM used in a
propagation house

• microscreens on vents/doorways of propagation
  houses
• scouting (e.g., yellow sticky cards)
• use of a natural predator (the midge Aphidoletes
  aphidimyza)
• natural pyrethrin insecticides (for populations
  too large for cultural, biological control)
• use of insect growth retardants (Enstar II
  specific to immature aphids)
• careful use (and rotation) of more toxic
  insecticides

11
Best management practices (as applied to nursery
and greenhouse plant propagation)

• a set of practices voluntarily adopted by
  nurseries and greenhouses to control irrigation
  and fertilization
• includes
• collecting run-off water when injecting
  fertilizer
• applying fertilizer only to obtain a growth
  response
• monitoring the quantity of irrigation (to prevent
  overwatering)
• recycling run-off water where feasible