Root Pruning but not Irrigation in the Nursery Affects Live Oak Root Balls and Digging Survival

Abstract

Abstract Irrigation placement and irrigation volume during field production of live oak (Quercus virginiana Mill.) in a sandy soil had no effect on trunk caliper [mean = 6.3 cm (2.5 in)] or tree height [mean = 3.8 m (12.4 ft)]. Root pruning had no impact on caliper and a slight (P < 0.06) impact on height. Irrigation placement and volume had little effect on number of cut roots at the edge of the root ball. Root pruning with a hand spade or in combination with root-pruning fabric placed under the liner at planting increased the number of roots at the edge of the root ball. Root pruning with fabric in combination with spade pruning increased the small-diameter (<5 mm) root weight: shoot ratio but reduced the total root weight: shoot ratio. Irrigation placement and volume during production did not affect summer nor winter digging survival. Trees that were not root pruned had poorer survival in the summer and winter digging seasons than those receiving either of the root-pruned treatments. In contrast, summer and winter survival was similar for root-pruned trees indicating that live oak can be dug in summer as well as the more traditional winter period as long as trees are root pruned during production. Trees pruned with fabric placed under the liner at planting in combination with spade pruning survived better than traditional spade root pruned trees.