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HERBICIDES TO CONTROL TREE ROOTS IN SEWER LINES
by John W. Groninger, Shepard M. Zedaker, and John R. Seiler
Abstract. The use of metham (methylcarbamadithioic acid) to control
tree roots obstructing municipal sewer lines faces possible restriction
by the U.S. EPA. In an effort to find a herbicidal alternative to metham,
eight presently available herbicides (asulam, DCPA, EPTC, MSMA, glufosinate,
glyphosate, sodium chlorate and triclopyr) were screened for efficacy in
killing roots without visibly damaging other portions of the tree. Exposed
roots in containerized seedlings of four species: water tupelo (Nyssa
aquatica L.), wax myrtle (Myrica cerifera L.), water oak (Quercus
nigra L.), and chinaberry (Melia azadarach L.), were exposed
to herbicides at rates equal to or 10 times the cost of operational rates
of metham. Five weeks following treatment, triclopyr, glufosinate and sodium
chlorate showed herbicidal activity against roots. Only glufosinate had
activity against roots without damaging foliage. Glufosinate was effective
at a 10x rate, but not 1x, the cost of metham. While these chemicals may
have the potential to be developed as alternatives to metham, increased
material costs would likely result.
COSTS ASSOCIATED WITH URBAN GYPSY MOTH CONTROL BY ARBORISTS: A CASE STUDY
by Christopher D. Vaughn, Thomas J. Straka, Donald L. Ham, Roy L. Hedden, and Kevin W. Thorpe
Abstract. The European gypsy moth, (Lymantria dispar L.)
is an introduced forest pest that has significantly impacted hardwood forests
and urban environments in the northeastern United States. In urban settings,
homeowners allocate significant financial resources to mitigate gypsy moth
damage. The objective of this study was to assess the costs of gypsy moth
control-related services provided by arborists to homeowners. At present,
cost information on this type of service is unavailable to urban resource
managers. Urban cost data will allow for comparisons of treatment alternatives
between residential and other urban situations. Cost data were obtained
from two large commercial tree care companies operating in the northeastern
United States. From these data, an average hourly rate of $104.70 was developed
for the two companies (excluding materials). This rate was broken down
into five major components: (1) labor, (2) overhead, (3) equipment, (4)
mobilization, and (5) profit. Labor, overhead, and equipment costs accounted
for approximately 48% of the total cost to the customer. Mobilization cost
which included travel and setup time accounted for approximately 15%. The
materials cost varied depending on the type of treatment chosen. Data reported
in this study are limited to hydraulic application.
DETECTION OF SALT AND WATERLOGGING
STRESSES IN ALNUS CORDATA BY MEASUREMENT OF LEAF CHLOROPHYLL FLUORESCENCE
by Glynn C. Percival and Geoffrey R. Dixon
Abstract. The measurement of chlorophyll fluorescence for use
as a rapid diagnostic tool which detected stress interactions in Italian
alder (Alnus cordata Desf.) is reported. Containerised trees in
well-drained or waterlogged conditions were subjected to foliar applications
of various concentrations of sodium chloride (NaCl). Measurements of leaf
chlorophyll fluorescence provided strong correlations with visual necrosis
(r2adj = 63.5%), and cell electrolyte leakage (r2adj = 84.6%). Leaf chlorophyll
fluorescence was not correlated with stem growth. Foliar applications of
NaCl increased sodium and chloride concentration in leaves irrespective
of whether trees were planted in well-drained or waterlogged compost, with
higher leaf Na and Cl concentrations reflecting the application of stronger
salt solutions. Except for decreased calcium, phosphorous, magnesium and
potassium in leaf tissue from trees grown in waterlogged compost and sprayed
with distilled water or 2% NaCl, no treatment effects upon macronutrient
concentrations were identified. Chlorophyll fluorescence values <0.8
indicated the onset of stress. The opportunities offered by measurements
of chlorophyll fluorescence to provide a diagnostic tool for arborists
are discussed.
WHITE PINE CHLOROSIS IN NORTHERN ILLINOIS: IRON DEFICIENCY OR NOT?
by A. Steven Messenger and Mark W. Stelford
Abstract. Eastern white pine (Pinus strobus L.) is a prized
ornamental. Its natural habitat includes a wide range of soil texture and
moisture conditions, leading to the assumption by many that this species
can be planted almost anywhere. Its performance in human-altered landscapes
demonstrates otherwise. One malady, symptomized by chlorotic foliage, has
been dubbed "white pine decline," and because alkaline soil is often associated
with this condition, iron deficiency has been postulated. Our studies,
conducted over a wide range of soil textures throughout northern Illinois,
confirm the negative role of soil alkalinity but lead us to reject the
hypothesis of iron deficiency. On the contrary, our data suggest iron efficiency
by this species.
EFFECT OF HERBICIDES ON BUTTERFLY POPULATIONS OF AN ELECTRIC TRANSMISSION RIGHT-OF-WAY
by W. C. Bramble, R. H. Yahner, and W. R. Byrnes
Abstract. A study was made in 1995 and 1996 of the butterfly populations
on a 500 kV transmission line of PECO Energy in the Piedmont Region of
eastern Pennsylvania. The objective was to compare the long-term effect
of 3 herbicide sprays with 2 mechanical methods of right-of-way (ROW) maintenance
on the number of butterfly species and their abundance. The wire zone/border
zone technique was used on all units to maintain shrubs on border zones.
Butterfly counts were made at 5 times over the growing season to coincide
with flowering of common plant species. There was no discernible adverse
effect of herbicide spray maintenance in comparison with mechanical methods
on either the number of species, or individuals, of the ROW butterfly population.
Twenty butterfly species were present on the handcutting unit and 19 to
21 on the 3 herbicide units. The number of individual butterflies present
on the 3 herbicide units ranged between 122 to 154 in contrast to 116 on
the handcut control unit.
SOIL COMPACTION ON CONSTRUCTION SITES
by Thomas B. Randrup
Abstract. Soil compaction was estimated on 17 construction sites and bulk densities were measured from the soil surface to depths of 1.0 m, at 0.1 m intervals, using a nuclear moisture/density probe. Soil on construction sites was heavily compacted at depths from 0.3 - 0.8 m. Suggestions for a new attitude to soil compaction on construction sites are made.