Group Title: Circular ;
Title: Cotton anthracnose /
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00102026/00001
 Material Information
Title: Cotton anthracnose /
Series Title: Circular ;
Physical Description: 4 p. : ; 23 cm.
Language: English
Creator: Stevens, H. E ( Harold Edwin ), b. 1880
Florida Cooperative Extension Service
Publisher: University of Florida, Division of Agricultural Extension
Place of Publication: Gainesville, Fla
Gainesville, Fla
Publication Date: 1918
Copyright Date: 1918
 Subjects
Subject: Cotton -- Diseases and pests -- Florida   ( lcsh )
Anthracnose -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by H.E. Stevens.
General Note: Caption title.
General Note: "March, 1918."
General Note: "Florida Cooperative Extension"--P. 2.
 Record Information
Bibliographic ID: UF00102026
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 226232998

Full Text



rcular 4 March, 1918


COOPERATIVE EXTENSION WORK IN
AGRICULTURE AND HOME ECONOMICS
UNIVERSITY OF FLORIDA DIVISION OF AGRICULTURAL EXTENSION AND UNITED
STATES DEPARTMENT OF AGRICULTURE COOPERATING
P. H. ROLFS, Director


COTTON ANTHRACNOSE*
BY H. E. STEVENS
Cotton anthracnose is a fungus disease widely distributed thru-
ut the cotton fields of the South, where it often causes a loss
f from 5 to 60 percent of the cotton bolls. It frequently injures
eedling plants and may be largely responsible for an imperfect
stand or an entire loss of the stand. This disease causes a loss
o Florida cotton growers each year that can be obviated if
roper precautions are taken.

APPEARANCE
The causal fungus attacks seedlings, the stems of older plants,
nd the bolls. Probably the greatest injury results from at-
acks on the bolls, commonly referred to as boll rot. On the
olls, the first indications of the trouble are small, round, dull
eddish-colored spots. One spot may gradually enlarge until it
overs from one-fourth to.one-half the boll. Several spots may
ome together forming irregular, diseased areas involving the en-
ire boll. In moist weather these spots or diseased areas are
oon covered with a pinkish coat, the spore masses of the fungus.
n dry weather this pink covering may fail to appear and the
pots are then gray or black. When the fungus enters the boll
t soon spreads thru the lint and seed, and if a diseased boll is
ut open the interior will be found discolored and rotten. Very
oung bolls when attacked may be killed or become distorted by
eason of the fungus penetrating one side while the other con-
inues to make normal growth, thus producing imperfect and
worthless bolls. The young bolls seem to be most susceptible to
attack and are easily invaded by the fungus if moist, warm
weather prevails.
Bolls slightly diseased or those that become diseased late in
heir development may mature and open normally; the seed

*Compiled from the work of Barre, Rolfs, Orton, and others.







Florida Cooperative Extension


usually contain the fungus, however, and if such seed are us
for planting they become the source from which anthracnose
spread to succeeding crops..
Infected seed containing spores or living internal parts of t
fungus germinate and may produce mature cotton plants, but t
fungus is most certain to appear on the parts of such plan
above ground and cause trouble at some period within the gro
ing season. Young seedlings from badly diseased seed are often
attacked and killed by the fungus before they appear abo
ground. After the seedlings are up, if weather conditions u
favorable for their growth prevail for a few days, the fungus ma
cause a severe damping off of the plants at the surface of t
soil. Damp, cold weather at this time may result in a materi
reduction of the stand. Seedlings that have damped off thr
attacks of the fungus will be found shrunken and dark color
at or below the soil surface.

HOW ANTHRACNOSE IS SPREAD
Anthracnose is a parasitic disease caused by the fungu
Glomerella gossypii. This fungus is a small microscopic plan
that reproduces itself in the diseased spots it forms on the cotton
plant. The pink coating observed on the surface of anthracnos<
spots is made up of countless spores (seed) of the fungus. Where
first formed the spores adhere in a sticky mass but they are late
dissolved by rain and heavy dew. Spores thus suspended ii
drops of water are blown about by the wind and carried by in
sects, animals, or any agent that comes in contact with the mois
tened, diseased plant. Under favorable conditions each sport
will produce a diseased spot and each spot will develop million
of new spores. This process may be repeated several times dur
ing a season and the disease be thus rapidly spread over the
field.
Diseased seed are the principal means by which anthracnose
is introduced into new fields or new localities. It has been thoro-
ly demonstrated that seed will retain the disease for varying
periods, and there is no known method of detecting diseased
seed by outward appearances. Spores adhering to the
surface of seed will remain alive for a year or more
and living parts of the fungus within the seed survive from two
to three years. When such seed are planted the disease is cer-
tain to develop on many of the plants.
Seed may become diseased in two ways. First, spores of the







Circular 4, Cotton Anthracnose


ngus may collect on and adhere to the surfaces of healthy seed
at have passed thru gins previously used for ginning cotton
affected with anthracnose. When badly diseased cotton is ginned
any fungus spores remain in the machine and these collect on
e seed of the next cotton to pass thru. Seed from perfectly
healthy cotton may become infected in this way. Such seed are a
source from which the disease may spread and should not be
wanted for two years or more unless treated to kill the fun-
us.
Second, seed containing internal living parts of the fungus are
ne of the most troublesome sources for spreading the disease.
eed obtained from diseased bolls or diseased plants are largely
f this nature. The fungus penetrates the immature seed coat
nd forms resting filaments inside which remain inactive until
he seed germinate. The fungus may attack the growing seed-
ing or appear later on the stem or bolls of the more mature plant.
he fungus can remain alive in such seed for a period of two or
three years, but after that time the seed may be safely used for
planting.
The fungus may also be carried over from one season to the
ext on the old stalks and bolls that remain in the fields. Where
he stalks are plowed under in the fall the fungus probably dies
ut in about nine months, but if the stalks are left standing the
ungus spores will remain alive twice as long. It is not advisable
o plant cotton on the same land that produced a crop badly in-
ected with anthracnose the previous year.

CONTROL
That cotton anthracnose can be controlled has been amply
demonstrated, and it may be eradicated from any field or locality
f cotton growers will observe the necessary precautions. Care
n selecting the seed for planting, and crop rotation will accom-
lish much in this direction in one or two years' time.
SEED SELECTION.-Disease-free seed is the most important fac-
or in keeping anthracnose in check. When seed are to be bought
he buyer should know whether they are diseased. A dependable
source of seed free from anthracnose is the grower's own field.
Seed selected from cotton plants that show no indications of an-
thracnose will produce cotton plants free from the disease. Such
seed may be obtained from fields showing the disease to some ex-
tent if care is used to pick cotton from healthy plants only and as
far removed as possible from those showing the disease. This







4 Florida Cooperative Extension

selected cotton should be kept separate from all other to avoid a
chance for contamination. It should be ginned separately aft
the gin has been cleaned and disinfected. A quantity of see
sufficient for next year's crop may be easily gathered in this wa
It is good practice for the cotton grower to set aside a certain
portion of land each year for seed production, especially in 1
calities where the disease is prevalent and desirable seed are har
to get.
PLANTING OLD SEED.-Old seed that have been properly care
for and kept dry afford a reliable source of disease-free seed. I
this case seed from diseased plants can be planted if the tim
element is not important. Such seed should be kept three year
to make sure they can be safely used, as the fungus will not sur
vive that period even within the seed. In certain localities where
anthracnose has been destructive growers and seed dealers kee
all cotton seed for three years before planting and the result
have been highly satisfactory in preventing losses from anthrac
nose. By this method seed from the commercial gins might b
made safe.
CROP ROTATION.-The anthracnose fungus may live a year o
perhaps a little longer on the dead stalks in the field. Hence,
rotation of crops is necessary to free an infected field from th
disease. Cotton should not be planted in the same field where th
disease was bad the previous year. If the infected fields ar
planted to some other crop for one year it is usually possible tc
grow cotton in that field the following year. Healthy seed
planted on disease-infected land will yield diseased cotton.
Deep, fall plowing in connection with crop rotation has giver
excellent results, especially when a cutter is first run over the
stalks and the land is carefully plowed to cover completely all
rubbish.




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