Miller, E. A.

Thornton, M. K.

English

Texas A&M University

L-174
ERADICATION OF JOHNSON GRASS
By
E. A. Miller, Extension Agronomist - M. K. Thornton, Agricultural Chemist
Texas A. & M. College System
Johnson grass is an excellent crop for hay and grazing but unfortunately it is
a pest in many cqltivated fields. It should be eradicated in fields because if not
controlled, it will spread and make the growing of crops unprofitable. However,
there is no easy way of killing this grass. Methods of control depend upon taking
advantage of its habits of growth. It increases both from seed and underground root-
stocks. The latter make it difficult to eradicate. Good methods for eradication
are (1) close grazing and plowing, (2) using sweetclover, (3) plowing without grazing
and (4) chemical treatment.
Grazing and Plowing • Close grazing, with cattle or sheep, i$ an effective way to
weaken this grass. It weakens the rootstocks and also prevents seed formation. Pas-
turing the grass or keeping it mowed will cause the deep rootstocks to die and the
new ones that form near the surface can then be exposed to the weather by shallow
breaking. The plowing is most effective when done in dry, hot weather. It should
be deep enough to turn up all the rootstocks. The important thing is to develop
shallow rootstocks by grazing or mowing, and then by plowing and harrowing, to expose
as many of them as possible to the hot summer sun. When this method is used, it
should be followed with a row crop such as cotton, and whatever grass remains should:
be destroyed by cultivation or with a hoe.
Using Sweetclover • In the Blackland Area a good plan is to grow biennial Madrid or
Evergreen sweetclover in the Johnson grass for grazing. The livestock like the grass
better than the clover and will keep it grazed down closely. As soon as they have
grazed it down they should be removed until the grass is again ready for grazing. By
repeating this several times during the summer and fall the Johnson grass will be
severely injured by the grazing and by the growth of the clover. The following spring
the biennial sweetclover will start growth earlier than the Johnson grass. This com-
petition will further weaken the grass. Then by repeating the alternate quick graz-
ing treatment the grass will be weakened still further. In this weakened condition
it can be killed easily by plowing the land after the clover has been grazed down or
harvested for hay or a seed crop. The land then could be planted to a late crop of
Sudan grass or a fall grain crop. Annual Hubam sweetclover also can be used in con-
nection with the grazing method.
Plowing • This method may be used where grazing or mowing is not practical. It con-
sists of plowing the land throughout the summer season before the shoots are ten days
old to expose as many of the rootstocks as possible to dry weather. Allowing the
shoots to grow a few days helps to exhaust the reserve food in the rootstocks. The
field then should be planted to a winter grain crop, such as oats or wheat or with a
row crop the following spring. All of the scattering plants that have escaped should
be removed by hoeing or with a chemical. This method requires1more plowing than where
the grass is first grazed because the rootstocks are more vigorous and deeper and it
is harder to get them to the surface or to exhaust their reserve food.
On sandy or sandy loam soils especially in West Texas sweeps may be used instead
of plows and the young shoots killed as soon as they have made about a week's growth
but never more than 10 days growth, thereby exhausting the reserve food in the root-
stocks. Allowing the plants to make a few days growth will exhaust the reserve food
in the rootstocks quicker than if no growth is made.
Chemical Treatment • Johnson grass can be controlled with some chemicals but unfortu-
nately on account of their cost they are practical only on small areas in the fields
and along fence rows, ditches and roadsides. Some effective chemicals are sodium
chlorate, Atlacide, Polybor-chlorate, Borascu, Concentrated Borascu, T.C.A., C.M.U.,
and Ammate. These chemicals, except T.C.A. and Ammate, sterilize the soil one or
more years, the length of time depending upon the soil type and amount of rainfall.
The T.C.A. ·and Ammate s.terilize the soil only a few months. They are effective in
killing the Johnson grass plants but are not effective in preventing reinfestation
from the seed in the soil.
Seedlings which may come from seed after chemical treatment should be destroyed
before they have developed rootstocks. They can be killed easily by cultivation be-
fore rootstocks have formed.
Amount of Chemical to Use • The amount to use varies with the different kinds of
chemicals. They should be used according. to the directions on the containers.
Plants which have been treated with chemical should not be grazed.
Caution: The chlorates, especially sodium chlorate, can be ignited easily by
f\iction when the solution dries on clothes or other organic material including wood.
They should not be dissolved on wooden floors. If clothes become wet with a chlorate
solution they should be washed immediately. The modified chlorates have other chem-
icals added which reduce the fire hazard.
Issued By
The Agricultural Extension Service
The Texas A. & M. College System and
The United States Department of Agriculture
G. G. Gibson, Director, College Station, Texas.
Cooperative Exten.ion Work in Alriculture and Home Economic •• The Texa. A. and Y. Collece Sy.t~1Il and the
United State. Department of Acriculture Cooperatine. Dhtributed in furtherance of the Act. of Conlre ••
of"', 8 and June 3 O. 1 914 •


Eradication of Johnson Grass.

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Eradication of Johnson Grass.

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