Effect of Nursery Production Method, Irrigation, and Inoculation with Mycorrhizae-Forming Fungi on Establishment of Quercus Virginiana

Abstract

Live oak (Quercus virgpiiana) 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 did 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. (6 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, fieldgrown, B&B nursery stock.