Tuesday, August 9, 2016: 2:45 PM
Valdosta Room (Sheraton Hotel Atlanta)
The objective was to determine the minimum amount of water required to maintain aesthetically pleasing landscape trees. Beginning in 2009, 63 trees produced in 27 L containers were transplanted into a sand soil under a double polyethylene covered, open-side gutter-connected greenhouse in Apopka, Florida. The first species were Quercus virginiana, and Ulmus parvifolia. Trees were transplanted in late August with abundant irrigation and allowed 6 months for root establishment. In late February the following year, irrigation volumes were estimated based average on trunk cross-sectional measured 30 cm above ground level, using models previously determined for each species derived from 5 to 6 years of weighing lysimeter data and daily ETo. Irrigation was based on ETo measured inside the structure and at 3 reduced percentages below 100%, to 55%. In late August tree farmers, municipal arborist, extension agent, master gardeners and homeowners rated 8 trees of each irrigation rate randomly distributed with the greenhouse. This was repeated in 2010 with Magnolia grandiflora and Acer rubrum; and in 2011 with Pinus elliottii and Ilex opaca ‘East Palatka’ species. Most species were rated aesthetically acceptable at irrigation rates of 55% of ETo. However shoot growth was greatly reduced. Acer rubrum trees all died.