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 22
AFM 91-19 / TM 5-629 / NAVFAC MO-314
24 May 1989
of subsequent germinating seedlings, especially
Section D -- Controlling Vegetation in Special
the grasses. Oryzalin kills germinating seeds, is
Areas
somewhat persistent in soil, but does not injure
most established plants.
3-12. Paved Areas. Vegetation that encroaches
on the edges of concrete or asphalt pavement, or
3-13. Roadsides and Rights-of-Way. Stump,
grows up through cracks and holes, causes
basal-bark, and foliage applications are excellent
premature breakdown of the pavement. Control
for controlling brush and trees along roadsides
with preemergence and postemergence applica-
and utility lines.
tions of herbicides is possible.
a. Several herbicides can prevent the emer-
a. The greatest hazards in rights-of-way treat-
gence of plants through cracks in pavement, but
ments are drift, runoff, improper application,
they vary in cost and in their potential to injure
and leaching to the roots of desirable species
vegetation adjacent to the paving. Suitable her-
under the treated areas.
bicides can be selected from attachments 4 and 6
b. Runoff is an important hazard on slopes,
based on their activity and persistence in soil,
bare ground, and pavements. Cutback asphalt,
and other characteristics. Bromacil, tebuthiuron,
applied after application of a soil sterilant, helps
prometon, and borate-chlorate mixtures are rec-
hold the chemical in place. Desirable trees and
ommended.
shrubs some distance from soil treated with soil
b. Shoulders immediately adjacent to the traf-
sterilants may be killed if their roots extend into
fic way, medians separating divided highways,
this treated area.
and islands at highway intersections are often
c. Before spraying, make a survey of the area
surfaced with asphalt. On these and similarly
to locate slopes subject to erosion and desirable
lightly paved areas, apply soil-sterilant herbicides
vegetation, and to determine size and density of
to the soil under the gravel base before it is
brush to be controlled.
"shot" with asphalt. Use the highest recom-
d. Cutting the trees and treating the stumps is
mended rates in attachment 6. The herbicide
most satisfactory for killing trees along road-
should be incorporated into the soil to a depth
sides, and for controlling brush over 30 feet tall.
of 4 to 6 inches, using a rototiller or disk. This
Considerable labor is required, but the danger
will activate the herbicide and improve weed
from falling branches is removed, and there will
control.
be no standing dead trees.
c. Do not use herbicide under asphalt or
e. Basal applications are practical for uncut
concrete pavement where roots of existing or
brush and for regrowth from cut brush or trees.
future landscaping shrubs and trees may extend
Make applications during the dormant season to
into the treated areas.
avoid danger of injury from drift. There is less
d. Care should be exercised to prevent dam-
danger of injuring desirable plants during their
age to desirable vegetation between the time of
dormant stage.
herbicide application and the time of paving.
Drainage water running across treated areas can
3-14. Weapons Ranges. When vegetation must
carry the herbicide to susceptible plants down
be controlled on weapons ranges that contain
slope.
unexploded ordnance, it may be cost-effective to
e. Residual effectiveness of treatments under
apply herbicides aerially. Assistance may be
paving depends on the factors discussed earlier,
obtained from the Air Force Aerial Spray
but, because of only limited percolation of water
Branch, 356 TAS/Aerial Spray, Rickenbacker
from above, herbicides should remain effective
ANGB OH 43217-5008, or commercial aerial
under paving for 5, 10, or even more years.
applicators.
f. Other treatments will be necessary to pre-
vent encroachment of weeds from unpaved areas
3-15. Railway Areas. Three distinct railway ar-
and to control vegetation growing up through
eas require weed control: the ballast, the road-
cracks in old pavement. Weeds emerging
bed, and the right-of-way.
through cracks can be killed by treatment with
a. The ballast is a 12- to 16-foot-wide strip,
herbicides such as paraquat and glyphosate.
made up of coarse material such as cinders and
These have no activity in soil, and they are not
gravel, that should be kept free of weeds.
likely to injure adjacent plants through runoff
Because it is porous, it does not retain herbicides
water. Including 2 to 4 pounds per acre of
well. Insoluble herbicides, those absorbed
oryzalin in such sprays will reduce establishment
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