Grant
No.: 102 Year of Award: 1986
Investigator:
Eugene B. Himelick
Title: Selection And
Propagation Of American Elms Demonstrating Resistance To Dutch Elm Disease And
The Phloem Necrosis Mycoplasma Disease
Key
Words: Dutch elm disease; phloem necrosis; tree
selection; disease resistance
Publications
Resulting From Grant: None
Summary
of Findings: This long-term research project is
designed to select possible cultivars of American elm that show resistance to
both Dutch elm disease and elm phloem necrosis.
Cultivars surviving intense screening for these two important shade tree
diseases will be released for planting in urban areas.
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 103 Year of Award: 1986
Investigator:
William R. Jacobi
Title: Fungicides For
Disease Prevention On Shade Trees
Key
Words: Fungicides; disease control; shade trees;
cankers
Publications
Resulting From Grant: Jabobi WR. 1989. Populus
problems: how to identify and cope with leaf spot diseases of aspen, cottonwood
and poplar. Amer. Nurseryman 169:48-55.
Jacobi WR. 1989. Resistance of honeylocust cultivars to
Thyronectria austro-americana. Plant Dis. 73:805-807.
Jacobi
WR. 1989. Effects of water stress on Thyronectria canker of honeylocusts. Phytopathol.
79:1333-1
Summary
of Findings: Cankers cannot be easily treated
with any fungicide. Honeylocust canker
infection was reduced by some fungicides but at such high rates that would
exceed the limits established by the U.S. EPA.
Thus, it is better to reduce the stress on a tree so it can better
defend itself. However, Marssonia leaf
spot on aspen can be effectively controlled with any registered fungicide.
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted: Rocky Mountain
Grant
No.: 104 Year of Award: 1986
Investigator:
Mark E. Ascerno
Title: The Impact Of
Date Of Elm Pruning On Elm Bark Beetle Vectored Dutch Elm Disease
Key
Words: Dutch elm disease; bark beetles; Ulmus
Publications
Resulting From Grant: Ascerno ME. 1991. Insect
phenology and integrated pest management. J. Arboric. 17:13-15.
Hahn JD & ME Arcerno. 1991. Public attitudes toward urban
anthropods in
Summary
of Findings: Success of any pest management
program requires knowing when to apply a treatment. Due to year to year weather variation, the
calendar method is the least precise.
Plant phenology is a more precise way to time treatments but it is
subject to years when insect and plant development are not well
synchronized. Phermone trapping can be
very precise but few tree and shrub insects have had their phermones analyzed
or synthesized. Insect phenology, the
direct relationship of insect development to weather, can be precise and has
been adapted for computer application.
Lower development threshold, degree day, cumulative degree days, model,
normal temperatures, and other observed temperatures, terminology used in computer-generated
predictions of insect development, are defined.
One computer program created by the
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted: Midwestern
Grant
No.: 105 Year of Award: 1986
Investigator:
T. Davis Sydnor
Title: A Comparison
Of Transplant Recovery Rates For Large Vs Small Trees
Key
Words: Transplanting; tree size
Publications
Resulting From Grant: None
Summary
of Findings:
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 106 Year of Award: 1986
Investigator:
Joe R. McBride
Title: Establishment
Success, Early Growth And Survival Of Street Trees In Relation To Site Factors
In The Urban Environment
Key
Words: Tree establishment; urban trees;
greenspace
Publications
Resulting From Grant: Nowak DJ, JR McBride &
RA Beatty. 1990. Newly planted street tree growth and mortality. J. Arboric.
16:124-129.
Summary
of Findings: Two-yr-old growth and mortality
rates were analyzed for 254 black locust, 199 southern magnolia and 27
Specialty
Interest: Commercial0, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted: Western
Grant
No.: 107 Year of Award: 1986
Investigator:
H. Dennis Ryan
Title: Safety
Training Curriculum For Arboricultural Firms
Key
Words: Tree safety; accidents; arboricultural
training
Publications
Resulting From Grant: Ryan HPD III & KA
Ertel. 1988. Arboricultural accidents -
cause and control. J. Arboric. 14:70-73.
Summary
of Findings: This research developed a
production and safety training program that can be used on the job site by
industry personnel. A literature review
and insurance data analysis revealed that the major accident expense to tree
care firms was worker compensation related injuries. A knowledge of required safety and production
related competencies could reduce the number of accidents. A safety competency needs analysis was
developed in conjunction with the National Arborist Association to guide
curriculum design. The competencies were
transformed into a training pro-gram which focused on groundsmen. A vest pocket guide, using a programmed
instruction format, was the major component.
Specialty
Interest: Commercial-1, Municipal-1, Utility -1,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 108 Year of Award: 1986
Investigator:
Michael N. Dana
Title: Shade Tree
Cambium Temperature As Influenced By Summer Wrap And Its Relation To Trunk
Damage
Key
Words: Stress physiology; water relations; urban
trees
Publications
Resulting From Grant: None
Summary
of Findings: These studies examined a possible
relationship between observed cambial necrosis of thin-bark shade trees
following summer trunk wrapping and high temperature injury of cambial
tissue. Lethal temperature for cambial
tissue of red maple (Acer rubrum L.) seedlings varied by exposure duration from
54C for 30 min. to 58C for 30 sec. In
the field under ambient summer conditions of full sunlight (if air movement was
restricted) cambial temperatures reached lethal levels. Controlled-temperature chamber studies
verified that trunk wrap elevates the mean temperature of the cambium, but that
the temperature on the illuminated side was not altered significantly by the
presence of the trunk wrap. Cambial
temperature under dark colored wrap material was several degrees higher than
under lighter colored wrap, and injury occurred at lower air temperatures.
Specialty
Interest: Commercial-1, Municipal0, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 109 Year of Award: 1986
Investigator:
Robert J. Joly
Title: Root Growth
Potential: Its Development In Shade Tree Nursery Stock Following Summer Digging
And Transplanting
Key
Words: Transplanting; growth regulators; Quercus
rubra
Publications
Resulting From Grant: Struve DK & RJ Joly.
1992. Transplanted red oak seedlings mediate transplant shock by reducing leaf
surface area and
altering carbon allocation.
Summary
of Findings: One-yr-old red oak seedlings
(Quercus rubra L.) from three open-pollinated families were produced in 1m tall
containers during 1989. In spring 1990,
the seedlings were either transplanted (which included pruning the main root to
a 15cm length) or not. Transplanted
seedlings either received a 5-s basal dip in 20 mM IBA or did not. The seedlings were placed in a greenhouse and
harvested at the beginning of the first lag phase, at the begin-ning of
elongation of the second growth flush, and 70 days after the beginning of the
experiment. Root-pruning removed 42 to
50% of whole-plant dry weight.
Transplanted seedlings had signifi-cantly reduced leaf surface area and
began a second growth flush later than untransplanted seedlings. There were no differences in CO2 assimilation
rate on a per unit leaf surface area. Predawn xylem water potential in
transplanted seedlings was lower than in untransplanted seedlings. Transplanted seedlings used less root and
more shoot reserves to develop the first flush than untrans-planted
seedlings. Treated root-pruned seedlings
with 20 mM IBA did not significantly increase growth potential compared with
untreated seedlings. For transplanted red
oak, transplant shock seems to be mediated through reduced leaf surface area,
which reduces whole-plant water use.
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 110 Year of Award: 1986
Investigator:
F.A. Baker
Title: Determination
And Monitoring Of Tree Moisture Demands In An Arid Environment
Key
Words: Moisture stress; water demand; xerophytes
Publications
Resulting From Grant: None
Summary
Of Findings: The results of this research
indicate that trees growing in arid environments demand far more water than can
realistically be pro-vided them.
Consequently, it is very important to select the right species when
growing trees under arid conditions. One
inch of water applied twice weekly was depleted from the root zone within 3
days.
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted: Rocky Mountain
Grant
No.: 111 Year of Award: 1986
Investigator:
Daniel A. Potter
Title: Biology,
Control And Host/Stress Realtionships Of The
Flat-Headed Apple Tree Borer In Nursery-Grown Maples
Key
Words:
Publications
Resulting From Grant: Dunn JP & DA Potter.
1990. Can tree susceptibility to borers be predicted from root starch
measurements? J. Arboric.
16:236-239.
Potter DA, GM Timmons & FC Gordon. 1988. Flat-headed
apple tree borer (Coleoptera: Buprestidae) in
nursery-grown red maples:
phenology of emergence, treatment timing, and response to stressed trees. J.
Environ. Hort. 6:18-22.
Summary
of Findings: The twolined chestnut borer (TLCB)
attacks and kills stressed oak trees, especially those that have been weakened
by severe drought. We tested the hypothesis
that winter root starch reserves of white oak are an indicator of tree vigor,
and that trees low in stored starch are especially vulnerable to borer attack
during the following summer. Only those
trees that were very low in stored root starch were heavily attacked by the
TLCB and showed signs of decline or died.
A few oaks with high starch reserves were also successfully colonized,
but those trees did not show signs of decline and did not die. Thus, winter starch reserves were generally a
good predictor of TLCB attacks. Further
reserach is needed to determine if this relationship holds for other hardwood
trees and their respective wood borers.
Use of root starch ratings to assess tree susceptibility to borers needs
further testing in urban settings to determine its practicality for pest
management.
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 112 Year of Award: 1986
Investigator:
Larry A. Rupp
Title: Drought
Tolerance And Water Use Efficiency Of Tree Seedlings
Key
Words: Water stress; water use efficiency;
drought tolerance
Publications
Resulting From Grant: None
Summary
of Findings: A line-source sprinkler system was
constructed for use in the greenhouse.
This system consisted of a fan-jet nozzle which runs along a track and
sprays downward onto a bench or floor.
Plants immediately beneath the nozzle receive the most water. The amount of water decreases with increasing
distance perpendicular from the path of the nozzle. Our goal was to use this system to evaluate
water needs of tree seedlings in container production systems. This effort was successful because of the
ability of seedlings to rapidly produce a leaf canopy which covered the top of
the conatiner and prevented a uniform, measurable amount of water from being
applied to each plant. Subsequent work
has shifted to field research and different styles of irrigation systems. There is good potential for use of this
technique in examining the role of water in tree seed germination.
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted: Rocky Mountain
Grant
No.: 113 Year of Award: 1986
Investigator:
Glen P. Lumis
Title: The Influence
Of Wire Baskets On Tree Growth
Key
Words: Containers; root function; ash;
hackberry; poplar
Publications
Resulting From Grant: Goodwin C & GP Lumis.
1992. Embedded wire in tree roots: implications for tree growth and root
function. J. Arboric. 18:115-123.
Lumis GP & SA Struger. 1988. Root tissue development
around wire basket transplant containers. HortSci. 23:401.
Struger SA & GP Lumis. 1988. Root/wire interactions of
landscape trees transplanted in wire baskets.
Summary
Of Findings: Experiments with 2-yr-old seedlings
of Fraxinus pennsylvanica and Celtis occidentalis and 2-yr-old whips of Populus
angulata x plantierensis were designed to study the effect of root girdling by
wire. Overall growth, foliar nutrient
content, xylem anatomy, root carbohydrate content, xylem water potential, and
rate of transpiration were studied 6 months after girdling. Neither greenhouse-grown seedlings nor
field-grown whips subjected to root girdling by wire grew less than those
without girdling wire. Full girdling
significantly reduced foliage dry weight in Fraxinus and the rate of
transpiration in Fraxinus and Celtis. A
gradient of water potential was observed in the xylem across the wire girdle in
seedlings of these two species. The
amount of carbohydrate present in root tissue and its distribution in relation
to the wire was slightly influenced by girdling in all three species.
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 114 Year of Award: 1986
Investigator:
Ida A. Leone
Title: The Role Of
Mycorrhizae In Adapting Woody Seedlings To Landfill Gas Conditions
Key
Words: Air pollution stress; mycorrhizae; Scotch
pine
Publications
Resulting From Grant: Weidman RC & IA Leone.
1987. Influence of mycorrhizae on growth and survival of Scotch pine seedlings
exposed to
landfill gas. Phytopathol. 77:123 (Abstr.).
Summary
of Findings: Pisolithus tinctorius, a symbiotic
fungus, was used to inoculate 2-yr-old Scotch pine seedlings in the greenhouse
and in the field at Edgeboro landfill in
Specialty
Interest: Commercial-1, Municipal0, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 115 Year of Award: 1986
Investigator:
Tim D. Davis
Title: An Evaluation
Of Several New Growth Retardants For Controlling Tree Growth
Key
Words: Growth regulators; triazole compounds;
growth inhibition
Publications
Resulting From Grant:
Walser RH & TD Davis. 1989. Growth, reproductive
development and dormancy characteristics of paclobutrazol-treated tart cherry
trees. J. Hort. Sci. 64:435-441.
Summary
of Findings: During the past 10 years much
research has been conducted on the response of plants to triazole-type plant
growth regulators. In this regard, there
is ample evidence to show that triazoles are potent inhibitors of shoot growth in a wide range of
plant species. The challenge with trees
is to deliver the growth retardant to the site of active growth (i.e. the
meristems) in a timely, uniform manner.
Once the triazoles begin inhibiting tree growth their effect may persist
from one to several years. This depends
on the dosage administered. In addition
to their well-known effects on shoot growth, triazoles have been found to
promote flowering in a variety of woody species. This response does not always occur and is
probably strongly influenced by dosage and timing of application. In addition to increasing the number of
flowers, triazoles have sometimes advanced flowering by several days. This could increase the chances for spring
frost damage and suggests that triazoles may influence tree dormancy.
Specialty
Interest: Commercial-1, Municipal-1, Utility -1,
General Interest0.
Chapter
in Which Research Conducted: Rocky Mountain
Grant
No.: 116 Year of Award: 1986
Investigator:
Eugene P. van
Arsdale
Title: The
Identifcation And Control Of Tree Root Pathogens In An Urban Environment
Key
Words: Disease control; root pathogens; urban
trees
Publications
Resulting From Grant: None
Summary
of Findings: This project involves injecting
water mold-killing fungicides such as metalaxyl and ethazole into the root zone
to reduce the effect of pathogens that attack the roots of landscape trees.
Specialty
Interest: Commercial-1, Municipal0, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 117 Year of Award: 1987
Investigator:
John R. Hartman
Title: Developing An
Educational Approach To Exposing And Preventing Construction Damage To Trees On
Wooded Lots
Key
Words:
Construction damage; tree survival; tree video
Publications
Resulting From Grant: Hartman JR & GM
Timmons. 1987. Effects of building construction on trees in wooded lots. ISA
videotape.
Timmons GM & JR Hartman. 1988. Avoidance of construction
damage on wooded lots. ISA videotape.
Summary
of Findings: Funding of this grant resulted in
the release of two videotapes dealing with the topic of how and why trees in
many wooded homesites fail to survive construction damage. The first tape shows actual building projects
where trees have been saved as opposed to projects where developers thought
they were saving trees; to sites where no precautions were taken to protect
existing trees. The second tape
illustrates the steps that can be taken to avoid damage to trees during
building construction.
Specialty
Interest: Commercial-1, Municipal0, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 118 Year of Award: 1987
Investigator:
Gary W. Watson
Title: The Role Of
Root System Development In A Comprehensive Shade Tree Management Program
Key
Words: Root development; tree management; shade
trees
Publications
Resulting From Grant: Watson GW & D Neely.
1994. The landscape below ground. Proc. International Workshop on Tree Root
Development in Urban Soils. International Soc.
Summary
of Findings: Concerns about root system
development of landscape trees should begin at propagation. Containerized plants often develop circling
roots that can lead to serious problems when they are planted out in the
landscape. Transplanting is an unnatural
process. During the time the root system
is regenerating, water stress can develop very quickly. The time required for the tree to establish
on its new site is affected by many factors, and may take years in northern
climates. Experienced horticulturists
will sometimes spend more time on preparing the planting site than on the
plant. Alkalinity, deicing salts, and
oxygen depleted rooting environments create unseen stresses for trees. Soil compaction and resulting poor aeration
are two of the biggest problems faced in the landscape. Incorporation of light-weight aggregates
before plants are installed can provide long-term benefits, but remedial action
is often the only choice. The most
current information available on these subjects is included in these
proceedings.
Specialty
Interest: Commercial-1, Municipal-1, Utility -1,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 119 Year of Award: 1987
Investigator:
James A. Robbins
Title: Screening Of
Pin Oaks For Resistance To Iron Chlorosis
Key
Words: n/a
Publications
Resulting From Grant: None
Summary
of Findings: (Grantee transferred to another
institution. Money returned)
Specialty
Interest: Commercial0, Municipal0, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 120 Year of Award: 1987
Investigator:
Paul J. Kalisz
Title: Efficacy Of
Vertical Mulching In Stimulating The Proliferation Of Tree Roots In A Fragipan
Soil
Key
Words: Vertical mulching; tree roots; water
status
Publications
Resulting From Grant:
Boettcher SE & PJ Kalisz.
1991. Single tree influence on arthworms in forest soils in eastern
Summary
Of Findings: We examined the effect of vertical
mulching on root growth and xylem water potential of large sugar maples (Acer
saccharum) growing in pastures. Root
mass in the 35-40cm depth of undisturbed soil was about 50% that in the 35-40cm
depth, and root mass at the edge of the canopy (7.5m from the trunk) was about
40% that found at one-fourth the distance to the edge of the canopy. After 3 growing seasons, the abundance of
roots in perlite-filled vertical mulch channels (0.6kg/m3) was signifi-cantly
(P<0.0001) less than undisturbed soil 1-2m away from the mulch channels
(4,4kg/m3) and in undisturbed soil immediately surrounding mulch channels (3.5kg/m3). Pre-dawn and and
Specialty
Interest: Commercial0, Municipal0, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 121 Year of Award: 1987
Investigator:
Gary A. Watson
Title: Water Stress
Variation In The Tree Crown And Its RelationTo Growth
Key
Words: Root:crown balance; transplanting;
construction damage
Publications
Resulting From Grant: Watson GW. 1990.
Directional variation in the growth of trees. J. Arboric. 16:169-173.
Watson GW. 1991. Attaining root:crown balance in landscape
trees. J. Arboric. 17:211-216.
Summary
Of Findings: 'Root:shoot ratio' is the term that
is often used to describe the relationship between the below- and above-ground
portions of plants. The term root:crown
balance is probably a better, more complete term, aand is considered as the
relationship between water and mineral absorption by the root system and utilization
by the crown. The root:crown balance is
affected by both physical and physiological changes. Perhaps the most extreme case of root:crown
imbalance occurs in transplanted trees or in root loss from construction
damage. Root:crown balance can often be
restored by : mulching, aeration. soil replacement and/or reducing crown size.
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 122 Year of Award: 1987
Investigator:
Salma N. Talhouk
Title: Influence Of
Water Deficit And Defoliation On Red Oak Physiology And Herbivor Performance
Key
Words:
Publications
Resulting From Grant: Nielsen DG. 1990.
Landscape integrated pest management. J. Arboric. 16:253-259.
Talhouk SN, DG Nielsen
& ME Montgomery. 1990. Water deficit, defoliation and Betula clones: short
term impact on gypsy moth (Lepidoptera: Lymantriidae) performance. Environ. Entomol.19:937-942.
Summary
of Findings:
Specialty
Interest: Commercial-1, Municipal0, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 123 Year of Award: 1987
Investigator:
Daniel A. Herms
Title: The Effects Of
Moisture, Nutrient And Defoliation Stress On The Resistance Of Paper Birch To
Bronze Birch Borer
Key
Words:
Publications
Resulting From Grant: None
Summary
of Findings: This study demonstrated that
drought stress is the most important factor predisposing paper birch to bronze
birch borer and that, in central
Specialty
Interest: Commercial-1, Municipal0, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 124 (ext. of grant #113) Year of Award: 1987
Investigator:
Glen P. Lumis
Title: The Influence
Of Wire Baskets On Tree Growth
Key
Words: Containers; root growth; ash; hackberry;
poplar
Publications
Resulting From Grant: Goodwin C & GP Lumis.
1992. Embedded wire in tree roots: implications for tree growth and root
function. J. Arboric.
18:115-123.
Lumis GP & SA Struger. 1988. Root tissue development
around wire basket transplant containers. HortSci. 23:401.
Struger SA & GP Lumis. 1988. Root/wire interactions of landscape
trees planted in wire baskets.
68:577-578.
Summary
Of Findings: Experiments with 2-yr-old seedlings
of Fraxinus pennsylvanica and Celtis occidentalis and 2-yr-old whips of Populus
angulata x plantierensis were designed to study the effect of root girdling by
wire. Overall growth, foliar nutrient
content, xylem anatomy, root carbohydrate content, xylem water potential, and
rate of transpiration were studied 6 months after firdling. Neither greenhouse-grown seedlings nor
field-grown whips subjected to root girdling by wire grew less than those
without girdling wire. Full girdling
significantly reduced foliage dry weight in Fraxinus and the rate of
transpiration in Fraxinus and Celtis. A
gradient of water potential was observed in the xylem across the wire girdle in
seedlings of these two species. The
amount of carbohydrate present in root tissue and its distribution in relation
to the wire was slightly influenced by girdling in all three species.
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 125 Year of Award: 1987
Investigator:
T. Davis Sydnor
Title: The Effects Of
Fertilizing Type And Level On Verticillium Wilt Of Woody Ornamentals
Key
Words: Disease control; fertilizer; Verticillium
wilt
Publications
Resulting From Grant: None
Summary
of Findings:
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 126 Year of Award: 1987
Investigator:
Nina L. Bassuk
Title: Improving
Transplanting Success By Managing Plant Growth And Water Relations
Key
Words: Transplanting; water stress;
antitranspirants; pruning
Publications
Resulting From Grant: Ranney TG, NL Bassuk &
TH Whitlow. 1989. Effect of transplanting practices on growth and water
relations of 'Colt' cherry trees during reestablishment. J. Environ. Hort.
7:41-45.
Summary
of Findings: Dormant pruning, a film
antitranspirant, and soil-applied paclo-butrazol were evaluated as
trasnplanting treatments in newly transplanted 'Colt' cherry trees under
irrigated and water-stressed conditions.
Under irrigated conditions all three treat-ments were effective in
reducing plant water loss. However, all
three treatments resulted in large reductions in mean growth rate, mean
relative growth rate, root dry weight and root surface area. The pruning treatment had no effect on the
leaf area:root area ratio, whereas the antitranspirant treatment resulted in an
increased leaf area:root area ratio, a response considered undesirable. Paclobutrazol decreased the leaf area:root
area ratio but also induced abnormal radial enlargement of plant roots. Under
water-stress conditions, all three treatments were effective in reducing plant
water loss and were successful in delaying plant water stress. Both pruned and antitranspirant treated
plants had improved relative growth rates as compared to the controls.
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 127 Year of Award: 1987
Investigator:
Edward F. Gilman
Title: Predicting
Root Spread From Stem Diameter And Branch Spread
Key
Words: Root growth; trunk diameter; crown
diameter
Publications
Resulting From Grant: Gilman EF. 1988.
Predicting root spread from trunk diameter and branch spread. J. Arboric.
14:85-89.
Gilman EF. 1989. Predicting root spread from trunk
diameterand branch spread. Arboricultural J. 13:25-32.
Gilman EF. 1988. Tree root spread in relation to branch
dripine and harvestable root ball. Amer. Nurseryman 168:85.
Summary
of Findings: Trunk diameter and branch crown
spread were linearly correlated with root spread in honeylocust (Gleditsia
triacanthos var. inermis), green ash (Fraxinus pennsylvanica), poplar (Populus
x generosa), red maple (Acer rubrum) and southern magnolia (Magnolia
grandiflora) but not in live oak (Quercus virginiana). Maximum root spread (excluding live oak)
ranged from 1.68 times the dripline for ash to 3.77 times for magnolia. Mean maximum root spread was 2.9 times the
dripline. Roots growing farthest from
the trunk were consistently near the soil surface.
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted: Southern
Grant
No.: 128 Year of Award: 1987
Investigator:
Robert G. Linderman
Title: Development Of
Norway Maple Rootstock Resistant To Verticillium Wilt
Key
Words: Disease resistance; Verticllium wilt;
Norway maple
Publications
Resulting From Grant: None
Summary
Of Findings: Rootstock seedlings of Norway maple
(Acer platanoides) grown in raised beds were infected with Verticillium
wilt. Cuttings from the surviving
seedlings were propagated and re-infected with the same fungus. Eventually we hope to develop rootstock which
exhibits genetic resistance to this disease, after which field trials will be
conducted to determine the level of resistance.
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 129 Year of Award: 1987
Investigator:
Randy R. Gaugler
Title: Enhanced
Effectiveness Of An Entomogenous Nematode Against Tree-Boring Insect Pests
Key
Words: Nematodes; artificial selection; genetic
improvement; host-finding ability; ultraviolet radiation
Publications
Resulting From Grant: Gaugler RR. 1989. Genetic
variability among strains of the entomopathogenic nematode Steinernema feltiae.
J. Nematol.
21:247-253.
Gaugler RR. 1989. Selection of host-finding in
Steinernemafeltiae. J. Invertebrate Pathol. 54:363-372.
Summary
of Findings: A systematic program of genetic
improvement was initiated by assessing the phenotypic variation of Steinernema
feltiae strains for two traits assumed to limit efficacy: UV tolerance and poor
host-finding ability. All of the strains
assayed showed both low UV tolerance and poor host-finding ability, indicating
that the likelihood of improving these traits through more extensive
popu-lation sampling is remote. Limited
genetic variation was detected among the strains for tolerance to UV,
suggesting that selective breeding for increased tolerance would be
inefficient. By contrast, highly
significant phenotypic differences were found with regard to host-finding
ability, suggesting that this trait would be responsive to selection. A genetically heterogeneous population was
constructed by round-robin mating of 10 strains; it will serve as the
foundation population for selective breeding.
Specialty
Interest: Commercial-1, Municipal0, Utility 0,
General Interest0.
Chapter
in Which Research Conducted:
Grant
No.: 130 Year of Award: 1987
Investigator:
James P. Dunn
Title: Carbohydrate
Reserves Of Oaks As An Indicator of Tree Vigor And/Or As A Predictor Of
Two-Lined Chestnut Borer
Key
Words: Tree vigor; pest management; two-lined
chestnut borer; Quercus alba
Publications
Resulting From Grant: Dunn JP & DA Potter.
1990. Can tree susceptibility to borers be predicted from root starch
measurements. J. Arboric.
16:236-239.
Dunn JP, TW Kimmerer & DA Potter. 1987. Winter starch
reserves of white oak as a predictor of attack by the twolined chesnut borer,
Agrilus bilineatus (Weber). Oecologia 74:352-355.
Summary
of Findings: The twolined chestnut borer (TLCB)
attacks and kills stressed oak trees, especially those that have been weakened
by severe drought. We tested the
hypothesis that winter root starch reserves of white oak are an indicator of
tree vigor, and that trees low in stored starch are especially vulnerable to
borer attack during the following summer.
Only those trees that were very low in stored root starch were heavily
attacked by the TLCB and showed signs of decline and did not die. Thus, winter starch reserves were generally a
good predictor of TLCB attacks. Further
research is needed to determine if this relationship holds for other hardwood
trees and their respective borers. Use
of root starch ratings to assess tree susceptibility to borers needs further
testing in urban settings to determine its practicality for pest management.
Specialty
Interest: Commercial-1, Municipal-1, Utility 0,
General Interest0.
Chapter
in Which Research Conducted: