24 May 1989
AFM 91-19 / TM 5-629 / NAVFAC MO-314
treated. In densely wooded areas, however, the
c. Apply basal spray to the lower 12 inches of
spray that penetrates to the lower levels often is
the woody plant to be killed. Wet the bark
inadequate to kill understory plants. A second
thoroughly all around the stem. Apply until it
aerial spraying may be necessary a year or two
runs down the stem to the base. One gallon of
after the first.
spray is enough to treat about 50 trees 2 inches
c. When applying spray by aircraft, instruct
in diameter or 33 trees 3 inches in diameter.
the pilot to fly as close to the top of the brush
d. Apply the herbicide with a compressed air
as safety allows. Use experienced flagmen or
sprayer, knapsack sprayer, or power sprayer.
guides on the ground to mark individual spray
Pressures from 10 to 40 pounds are adequate. A
swaths to guide the pilot. Flagmen should move
15 to 20 degree fan-type nozzle set at a 45
upwind during flagging to minimize their expo-
degree angle to the spray wand is preferred.
sure to spray drift. Swath width should not
exceed 1.5 times the wing span or bladespan of
3-10. Cut Surface and Injection Treatments:
a. Trees larger than 5 inches in diameter are
d. The possibility of drift, and in some case
treated with these methods because their bark
volatilization, must be dealt with in any spray
often is too thick for basal sprays to penetrate.
application. None of the herbicides discussed in
These treatments are also effective for lesser
this publication are high-volatile esters. How-
diameters. Frills or notches made by an ax into
ever, low-volatile esters of phenoxy herbicides
the sapwood, encircling the tree, act as cups to
can volatilize at high-temperatures, especially
hold the herbicide. The frill can be filled with
above 90F. Even with products that do not
solutions of 2,4-D, dicamba, picloram, and
volatize, proper precautions should be taken to
triclopyr. Undiluted herbicides or AMS crystals
avoid drift to nontarget areas in a spray applica-
(or a strong solution in water) can be used.
tion (figure 2-2).
There are also mechanical injection tools avail-
e. All crewmembers should review applica-
able that make the cut into the tree bark and
tions techniques before the application season
inject the herbicide in one operation.
begins. Also, before application is begun on a
b. If trees are felled, the freshly cut stumps of
site, a reconnaissance should be made of the
sprouting species should be treated with the
area to be treated. Streams, impounded water,
above herbicides to prevent sprouting. Most
crops, gardens, dwellings, buffer zones, and
hardwood species will sprout after cutting.
roads should be delineated on a map. Avoid
applying herbicides where they are not wanted.
Except for herbicides registered for use on lawns
3-11. Soil Treatments:
and ornamental plantings, plan to leave uns-
a. Herbicides are applied to the soil around
prayed zones of vegetation around gardens,
and under woody plant canopies as dry granules
dwellings, or other buildings housing people or
or as water sprays. The soil should be moistened
serving as public gathering places. Avoid spray-
either by rainfall or irrigation shortly after
ing herbicides, other than aquatic herbicides,
herbicide application for best results. The herbi-
directly into flowing streams, drainage ditches,
cide must be one of those that are active
and impounded water.
through soil absorption and must be carried into
the soil to be effective. Reduced effectiveness
often results when there is a hot, dry season
3-9. Basal Sprays. Some herbicides kill trees if
applied to the trees' lower trunks.
b. Herbicides can also be distributed in grid
a. Basal sprays are applied to the bark of
patterns or bands encircling the plants, or in any
individual trees up to 5 inches in diameter. They
other suitable placement that will bring the
can be used at any time of the year, but
herbicide into contact with the tree roots. Use
effectiveness is reduced when the bark or soil is
strip applications to minimize damage to desir-
able grasses growing under and near trees to be
b. Herbicides used in this manner include
esters of 2,4-D and other phenoxy herbicides
c. Herbicides for soil treatment for brush
mixed in diesel oil or kerosene. Usually mix
control include: bromacil, picloram, and tebu-
at a rate of 12 to 16 pounds of herbicide in
100 gallons of oil. Water is an ineffective car-
rier. Other herbicides are also used as basal
d. Runoff water can carry herbicides to adja-
cent areas downslope and kill desirable plants.