| Live oak (Quercus virginiana) trees were grown to about a
2.5 in (6 cm) caliper in various container and field production systems,
then transplanted to a landscape with and without mycorrhizae-forming spores
under two irrigation regimes. Trees grew at nearly the same rate in the
nurseries, regardless of production method. However, root distribution was
altered. Low profile, air root-pruning containers had less roots on the
outside surface of the root ball than traditional plastic containers. Application
of mycorrhizae-forming fungi to the backfill soil at planting in a landscape
had no impact on live oak the first 30 months after planting. However, nursery
production method and irrigation frequency following planting had a huge
influence on tree survival. Irrigating 2.5 in (5 cm) caliper live oak for
only 6 weeks after planting in spring in a slightly drier than normal year
resulted in 43% tree death rate. Irrigating twice each week through the
first summer after planting in spring kept all trees alive. Under limited
irrigation conditions, trees from containers died sooner and more trees
died than field-grown B&B trees. Root-pruned field-grown B&B trees
survived better than all others following transplanting. Trees planted from
all nursery production methods survived and grew similarly provided they
were irrigated regularly through the first growing season. Under limited
irrigation, landscape managers would obtain the most live trees by planting
root-pruned, field-grown B&B nursery stock. |