Select a title from the list below to see an abstract of the article. For information about ordering reprints of complete articles, contact ISA at (217) 355-9411 or isa@isa-arbor.com.
Red Oak Transplanted to Different
Bulk Density Soils Have Similar Water Use Characteristics
by Cathy Maupin and Daniel K. Struve
Abstract. Container-grown red oak (Quercus rubra L.) produced
in two bulk density growing media (0.4 or 0.9 g cm-3) were transplanted
into larger containers filled with Wooster silt loam soil compacted to
1.25, 1.50 and 1.75 g cm-3 densities. Growing media bulk density
affected only the number of shoots elongating; there was no significant
difference in stem diameter, shoot length and dry weight, leaf area and
dry weight and regenerated root dry weight between plants grown in the
low or high bulk density production media. Transplant media bulk density
affected stem diameter in shoot length; both were significantly less when
plants were transplanted to 1.75 g cm-3 than to the 1.50 g cm
-3 bulk density soil. Water use, expressed either as whole plant
or per unit leaf area, was greater for plants transplanted to 1.50 g cm-3
bulk density soil than those transplanted to 1.25 or 1.75 g cm-3
soil at only three times during the 80 day water use study period: 39,
55 and 69 days after leaf emergence. Transplanting container-grown red
oak to high bulk density soils did not greatly affect regrowth potential
under non-limiting soil moisture conditions.
Root Response of Mature Live Oaks
in Coastal South Carolina to Root Zone Inoculations with Ectomycorrhizal
Fungal Inoculants
by Donald H. Marx, Michael Murphy, Teresa Parrish, Selina Marx, Dennis
Haigler, and Dorie Eckard
Abstract. New fine root growth and ectomycorrhizal develop-ment
were determined for mature live oak (Quercus virginiana) growing
in a stressed landscape after soil injection of ectomycorrhizal fungal
(Pisolithus tinctorius Pt) spores with or without fertilizer (12-48-8)
or after vertical mulch application of a mix of Pt spores, soil-enriching
bacteria, various organics, and water-managing gels. After 6 months, the
injected spores stimulated more ectomycorrhizal development than the fertilizer
or water-only control treatments. When spores and fertilizer were applied
together, they increased by four times the fine root biomass and by three
times the ectomycorrhizal development than observed in the water-only control.
The estimated relative root absorbing potential of the roots was 14 times
that of the control. After 4 or 6 months, the vertical mulch treatment
stimulated six times more fine roots and twice the ectomycorrhizal development
found in the control treatment. These differences reflected an 8 to 12
fold increase in the relative root absorbing potential of the fine roots
and ectomycorrhizae. In both studies, Pt ectomycorrhizae accounted for
over half of the ectomycorrhizal development. Natural ectomycorrhizal development
ranged from 18 to 38 % of fine roots in control treatments. The results
demonstrated that Pt spore and bacterial inoculants can be successfully
introduced into the root system of mature live oaks in a stressed environment,
increase fine root growth, and form abundant ectomycorrhizae.
Evaluation of a Pan Evaporation
Model for Estimating Post-planting Street Tree Irrigation Requirements
by David Sivyer, J. Roger Harris, Naraine Persaud, and Bonnie Appleton
Abstract. Budget restraints force many cities to rely on volunteers
for street tree irrigation. Reliable, easy to follow recommendations are
needed. Using a pan evaporation model created by others, we developed a
method for predicting irrigation amount and frequency for street trees
and tested it on mulched, 3-in (7.5 cm) caliper, balled and burlapped Pyrus
calleryana 'Redspire' (pear) and Betula nigra 'Heritage' (birch)
trees five months after planting. The model predicted that root balls should
be saturated every 3 days with 10 gal (38 l) of water. When tested against
control trees which were irrigated on an "as needed" basis according to
root ball moisture sensors, model trees required a total 130 gal (494 l)
each of water, while pear and birch controls required an average of 108
and 122 gal (410 and 464 l) each, respectively, over the experimental period
of two months. However, pear and birch controls required 25 and 24 site
visits respectively, whereas model trees required only 13 visits. Refitting
the model assumptions with actual tree measurements and adjusting the root
ball soil tension point at which root balls were to be irrigated to well
above the permanent wilting point, resulted in a 5 gal (19 l), every 3
day regime.
Effects and Control of Periodical
Cicada Magicicada Septendecim and Magicicada Cassini Oviposition
Injury on Urban Forest Trees
by Fredric D. Miller
Abstract. The long-term effect of oviposition by the female periodical
cicadas, Magicicada septendecim and M. cassini (Homoptera:
Cicadidae) was examined on shade trees at two urban forest sites in northeastern
Illinois following the 1991-1993 growing seasons. Minimum branch diameter
appears to be a critical factor in ovipositional activity. Plants with
stout branching habits do not appear to be suitable for oviposition. Percent
canopy flagging, as a function of the number of wounds per branch, may
not be an accurate measurement of ovipositional damage. Young trees with
stem diameters or main scaffold branches with diameters between 5 and 10
mm may experience significant damage to the main trunk resulting in breakage
and significant growth loss. Larger plant material does not appear to be
significantly affected by ovipositional damage, which results only in a
minor natural pruning event. Chemical control for the prevention of ovipositional
wound damage by the female periodical cicada does not appear to be a practical
and effective pest management option. Even severe and heavy ovipositional
damage does not appear to predispose urban forest trees to attack by secondary
insects or pathogens.
Tree Root Response to Circling Root
Barriers
Laurence R. Costello, Clyde L. Elmore, and Scott Steinmaus
Abstract. Root system size and distribution were measured for
Raywood ash (Fraxinus oxycarpa 'Raywood') and Lombardy poplar (Populus
nigra 'Italica') planted with and without circling root barriers. Trees
with circling barriers had fewer numbers of roots than controls (no barriers),
but mean root diameters were similar. Root depth 30 cm outside barriers
was greater for trees with barriers, but at 90 and 150 cm away, depth was
equivalent to controls. Roots tended to grow toward the soil surface after
growing under the barriers. No consistent differences in root response
to any of the four types of barriers tested were found for either species.
Soil cultivation during the installation of a subsurface barrier (used
to simulate a hardpan) resulted in lower soil bulk densities and a deeper
distribution of roots in the soil profile than in plots which were not
cultivated. Reducing soil bulk densities that are limiting to root growth
may be an important consideration when using circling root barriers.
What Makes a Big Tree Special? Insights
from the Chicagoland Treemendous Trees Program
by Susan C. Barro, Paul H. Gobster, Herbert W. Schroeder, and Stephen
M. Bartram
Abstract. In 1995, a local version of the American Forests big
trees program (Treemendous Trees) was initiated in the Chicago area by
Openlands Project and the Morton Arboretum. In addition to the numerical
information about tree sizes required on the nomination form, many participants
attached notes and sometimes lengthy letters that detailed various aspects
of the nominated trees. A qualitative analysis of these written materials
identified a number of recurrent themes that sometimes went far beyond
the physical size dimensions to describe aesthetic and functional values,
and symbolic and emotional meanings. This information may help urban foresters
better understand the breadth and depth of values people have for urban
trees--particularly large ones. Results also have implications for obtaining
more and better information from big tree programs, and for using these
programs as vehicles for developing collaborative partnerships between
urban foresters and citizens in knowledge discovery and sharing.
Developing a Utility Line
Arboretum
by Bonnie L. Appleton, Barbara M. Touchette, Susan C. French, and Alex
X. Niemiera
Abstract. Distribution of publications discouraging the practice of planting inappropriately-tall trees under utility lines has not been particularly effective as evidenced by their continuing selection. To create higher visibility of both this problem and one solution, the use of smaller trees as well as large shrubs, a utility line arboretum was developed to showcase potentially superior tree and shrub selections for the utility line - street tree conflict area.