Monks and Larry Bass
are unwanted plants in gardens, reduce available moisture, nutrients,
sunlight and growing space needed by crop plants. Their presence
can reduced crop growth, quality and yield. In addition, they can
make harvest difficult. Weeds also provide cover for diseases, insects
and animals (rodents, box turtles, snakes, etc.). Garden weeds are
hard to control because they grow rapidly, produce vast numbers
of seeds, and spread aggressively by vegetative structures and/or
seeds. There are several methods that should be used in a combined,
coordinated effort to control weeds. They include cultural, mechanical
and chemical methods.
vegetable crops can effectively suppress weeds by shading. Thus,
one method of weed control is to select a crop that is capable of
suppressing (shading) weeds. The following vegetable crops are listed
according to there ability to suppress weeds.
of Crops to Suppress Weeds
of weeds by crops works best when the crop germinates quickly an
gets a head start on weeds. To achieve this, plant crops at the
proper depth, with adequate moisture and fertility. Also, it is
important to purchase high quality vegetable seeds or transplants
that are free of weed seeds or seedlings. Garden soils should be
tested and soil test recommendations followed to stimulate rapid
crop growth capable of weed suppression.
'smother' crops can be used to reduce weed germination in succeeding
crops. For this purpose, smother crops are usually planted in the
fall and killed by tillage or chemicals the following spring prior
to planting vegetables. The straw residue from smother crops (i.e.
rye, ryegrass, etc.) can inhibit early season germination of weeds
such as common lambsquarters, common purslane and redroot pigweed
by 75% or more. NOTE: Avoid planting smother crops where small seeded
crops such as lettuce will be seeded the following year or duction
in germination can occur. Smother crops are also effective in suppression
of many winter annual weeds such as henbit and chickweed. Rotate
crops to different areas of the garden, so a specific crop is never
planted in one area for two years in a row, to prevent the increase
be used to prevent weed germination and growth, and ultimately reduce
time and labor required to remove weeds. Mulches fall into two categories
-- organic mulches are derived from plant material and decompose
naturally in the soil, and inorganic mulches which do not decompose
and therefore must be removed from the soil after serving their
moisture retention, soil warming, and weed reducing purposes.
Some of the most commonly used organic mulching materials are manures,
bark chips, ground corncobs, sawdust, grass clippings, leaves, newspapers
(shredded or in layers), and straw. Organic mulches allow some flexibility
in fertilizing and watering since they can be raked back from the
plants. They should normally be applied uniformly three to six inches
deep around the base of the getable plant. Do not mulch with straw
containing weed seeds. If straw contains weed seeds it should be
moistened throughout, kept moist until the weed seeds germinate,
and then air dried several times to kill germinating seedlings.
Black plastic is the most frequently used inorganic mulch. Clear
plastic is not recommended because it does not exclude the light
that weed seeds need to germinate. Gardeners should make sure there
is adequate moisture in the soil before any mulch is applied, especially
plastic films. It is also necessary to apply most of the fertilizer
required by the plants before the plastic is installed. There are
also several durable weed fabrics that are very effective in weed
suppression. They are capable of lasting up to 20 years or more
when covered with soil.
of whether to use an organic or inorganic mulch really depends on
the season of the year and what the gardener is trying to accomplish.
Organic mulches should be applied after the soil temperature has
warmed in the spring. If applied to cold soils, the soil will warm
slowly and the growth rate of most vegetables will be reduced. Inorganic
mulches can increase the soil temperature by at least 6-8F. Therefore,
their greatest value is early in the growing season when soils are
weeds present at seeding or transplanting are capable of growing
rapidly, it is important to kill all weeds prior to planting. Weeds
that emerge after planting should be removed early before they are
past 3 inches tall. Large weeds are difficult to remove without
uprooting vegetable plants. Early season competition which may reduce
crop growth, yield, and quality may also occur if weeds are allowed
to remain past the 3- inch stage. Removal by hand or cultivation
can be used to rid the garden of weeds. With removal by hand, weeds
can be hand pulled or removed using hand tools. Several small hand
tools are available that are very effective on small weeds and for
working near garden plants. They include the springtooth and cultivator
and the trowel. These tools limit the gardener to working solely
on their knees.
There are a
variety of effective tools that allow the gardener to stand while
removing weeds. They include the scuffle hoe, the Warren hoe, the
onion hoe, and the Garden Weasel. Scuffle hoes come in several shapes
and are "push-pull" weeders that require no lifting. Perhaps, the
most popular is the Dutch version, an open stirrup with a blade.
Others consist of triangular plates. Most scuffle hoes are very
light weighted and are effective on small weeds. The Warren hoe
has an arrowhead shape. It is effective in removing small weeds.
It can be used to scratch a furrow with one end and when turned
upside down the two shoulder points fill in the furrow. The onion
hoe is a thin bladed hoe that is recommended when removing weeds
near vegetable plants. It is easier to handle than large, heavy
hoes. Onion hoes can be made by simply grinding a common hoe so
the blade is thin. This will allow more precise maneuvering near
vegetable plants. The Garden Weasel has three sets of wheels with
spikes that you "push-pull" to cultivate weed. It is recommended
where numerous small weeds are present. The Garden Weasel is also
useful in breaking soil crust to aid vegetable crop emergence.
can be used to cultivate weeds. Push plows, also called push cultivators,
are inexpensive and also very effective in killing small weeds.
The large wheel versions are usually easiest to push. For large
weeds, a garden tiller or small tractor is most effective. Regardless
of the implement, cultivate no deeper than 2 inches deep to prevent
root damage to vegetable plants. Cultivators should normally be
adjusted to throw soil around the base of crop plants and over any
emerged weeds that are present in the row. Row spacing can be adjusted
to allow close mowing near the soil surface to control weeds. Self-propelled
rotary or sicklebar mowers and/or mowers with large rear wheels
are easiest to maneuver. Weedeaters fitted with plastic string can
also be used to cut weeds near the soil surface.Extreme care should
be used for crop and personal safety. See manufacture's warnings
prior to operating all equipment.
another weed control aid that some gardeners employ. Gardeners should
be aware that NO SINGLE HERBICIDE WILL DO THE ENTIRE JOB of controlling
weeds in all vegetable crops. There is also a problem of applying
relatively small amounts of the herbicide evenly to the garden surface.
Miscalculation of rates or miscalibraion of applcation equipment
can cause some areas of the garden to get too much or too little
of the herbicide. Under-application will result in poor weed control
while over-application will result in damaged plants.
For small areas,
several chemical manufacturers (e.g. Fertilome,Ortho, Scott, Security,
and others) sell a variety of herbicides in small quantities which
are ideal for this job. These chemicals are usually formulated to
make them more convenient and easier for the homeowner to apply.
For larger areas, several products can be purchased can be purchased
at farm chemical retail stores.
For all purpose
weed control when no crop is present (either in the fall, later
winter, or early spring), use Roundup or Finale. This material,
applied over the top of weeds, will kill all weeds. Do not use this
material when crops are present or serious injury will occur.
IN VEGETABLE GARDENS
To control germinating
weed seedlings before the crop emerges, two major herbicides are
available to choose from. These materials are DCPA (Dacthal) and
trifluralin (Treflan). These trade names (listed in parentheses)
are the more commonly marketed forms of these herbicides. However,
these herbicides may be marketed using other trade names and the
buyer should read the ingredients list to be sure that the common
name of the herbicide, which is listed before the trade name, appears
on the label. Weed control chemicals are available as concentrated
liquids, (2 to 8 lb/gal) which need to be mixed with water before
applying; as wettable powders which are from 50 to 100% active ingredient
and need to be dispersed in water for uniform application, or as
granules which are from 1 to 10% active ingredient and which are
applied dry with granular applicators. Consult the chart at the
end of this section for specifics on labeled crops and timings.
Unless otherwise indicated on the chart, the chemicals may be used
either at planting or at transplanting.
can be controlled using hand removal, cultivation (see previous
discussion) or sethoxydim (Poast) herbicide. It is usually effective
when applied to grasses that are no larger than 4 inches tall. Consult
the chart at the end of this section and the herbicide label for
specifics on use, labeled crops and timings. Never exceed the recommended
rate, as severe plant injury may occur.
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