Have you ever noticed that some weeds are killed by one particular
method, but that this same method may entirely fail to kill other kinds
of weeds? If we wish to free our fields of weeds with the greatest ease,
we must know the nature of each kind of weed and then attack it in the
way in which we can most readily destroy it.
The ordinary pigweed (Fig. 56) differs from many other weeds in that it
lives for only one year. When winter comes, it must die. Each plant,
however, bears a great number of seeds. If we can prevent the plant from
bearing seed in its first year, there will not be many seeds to come up
the next season. In fact, only those seeds that were too deeply buried
in the soil to come up the previous spring will be left, and of these
two-year-old seeds many will not germinate. During the next season some
old seeds will produce plants, but the number will be very much
diminished. If care be exercised to prevent the pigweed from seeding
again, and the same watchfulness be continued for a few seasons, this
weed will be almost entirely driven from our fields.
A plant like the pigweed, which lives only one year, is called an
_annual_ and is one of the easiest weeds to destroy. Mustard, plantain,
chess, dodder, cockle, crab grass, and Jimson weed are a few of our most
disagreeable annual weeds.
The best time to kill any weed is when it is very small; therefore the
ground in early spring should be constantly stirred in order to kill the
young weeds before they grow to be strong and hardy.
The wild carrot differs from an annual in this way: it lives throughout
one whole year without producing seeds. During its first year it
accumulates a quantity of nourishment in the root, then rests in the
winter. Throughout the following summer it uses this nourishment rapidly
to produce its flowers and seeds. Then the plant dies. Plants that live
through two seasons in this way are called _biennials_. Weeds of this
kind may be destroyed by _cutting the roots below the leaves_ with a
grubbing-hoe or spud. A spud may be described as a chisel on a long
handle (see Fig. 58). If biennials are not cut low enough they will
branch out anew and make many seeds. Among the most common biennials are
the thistle, moth mullein, wild carrot, wild parsnip, and burdock.
A third group of weeds consists of those that live for more than two
years. These weeds are usually most difficult to kill. They propagate by
means of running rootstocks as well as by seeds. Plants that live more
than two seasons are known as _perennials_ and include, for example,
many grasses, dock, Canada thistle, poison ivy, passion flower, horse
nettle, etc. There are many methods of destroying perennial weeds. They
may be dug entirely out and removed. Sometimes in small areas they may
be killed by crude sulphuric acid or may be starved by covering them
with boards or a straw stack or in some other convenient way. A method
that is very effective is to smother the weeds by a dense growth of
some other plant, for example, cowpeas or buckwheat. Cowpeas are to be
preferred, since they also enrich the soil by the nitrogen that the
Weeds do injury in numerous ways; they shade the crop, steal its
nourishment, and waste its moisture. Perhaps their only service is to
make lazy people till their crops.
You should learn to know by name the twenty worst weeds of your
vicinity and to recognize their seeds. If there are any weeds you
are not able to recognize, send a sample of each to your state
experiment station. Make a collection, properly labeled, of weeds
and weed seeds for your school.
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