Contamination free cotton
‘implementation of the Cotton Standardization and
Grading System (CSGS) at the grassroots level is vital
for the promotion of contamination free and clean cotton
production in the country’, but ‘transmission and
adaptation of contamination free cotton production
technology’ still stands as a big question for
producers; because most of the cotton growers, ginners
and other producers or probably all didn’t know that,
hence it needs special attention, which is actually
basic need of today as well as tomorrow, when we must
compete in market with all rules and regulations of WTO.
Therefore I will try to review present situation with
the help of importance and historical background of
crop, its diseases and then try to explain the causes,
symptoms and non-chemical control of cotton diseases
because the diseases are also major cause and most
important factor for production of contaminated cotton.
It is hoped that this presentation will be beneficial
for cotton growers and serve as a reminder for
researchers so that they could plan their future
strategies and for extension workers so that they may to
However, cotton is one of the most important fiber and
cash crops of Pakistan, which earns foreign exchange for
the country. The crop has maximum area in Punjab
followed by Sindh and very negligible in NWFP. The yield
per hectare of seed cotton in Punjab is more to that of
Sindh province. Archaeologists and historians believe
that cotton existed 5000 years ago. Mohan-jo-Daro was
nature place of cotton, where the people knew the arts
of spinning and weaving. Cotton lint was separated from
seed on charkha (a kind of hand cranked roller gin) and
the fibers processed in to fabrics with drop spindles
and primitive looms. The quality of the textile produced
has been excellent.
The history of ‘cotton crisis’ is also as old as its
cultivation, therefore, that may also not to be ignored.
Following poem of Shah Abdul Latif, a saint poet of
Sindh can be quoted as first example (during 1689-1752
The second example regarding cotton diseases was quoted
in Taxas Agricultural Experiment Station Bulletin No.4
(1888). Palmel studied and wrote about root rot of
cotton. The struggle against cotton diseases continued
up to date. It had been revealed that this crop was
subjected to more than 60 diseases. The diseases reduced
the yield and brought about heavy losses. The work
carried out so far in Pakistan shows that seedling rot
or wilt, root rot, boll rot, anthracnose, different
types of leaf spot diseases, premature opening of bolls
(Tirak), stunting and reduction in size of leaves, some
nematode species, bacterial blight (angular leaf spot
and boll rot), leaf curl and stenosis of cotton, found
causing damage to the crop. Such diseases are injurious
in some areas, in some years and on some plant parts.
The magnitude of disease damage depends up on the
environment and cultivar.
The crop record revealed that root and boll rot diseases
of cotton were considered as most severe and
destructive, but since last decade, cotton leaf curl
virus (CLCV) found to be most important disease. This
disease was first time recorded in 1967 at Multan on
cotton plants. In Sindh, this disease was first reported
during 1996 at Ubauro, District Ghotki. CLCV crossed New
Saedabad, District Hyderabad during 1999-2000. It was
considered a minor disease until 1987, but in 1991-92,
it infested 35,000 acres and 294,000 acres during
1992-93 causing a huge production and monetary loss to
However, at present, shortage of irrigation water is
major threat to cotton crop. Therefore proper irrigation
to the crop must be assured at proper time with proper
dose. The adaptation of modern irrigation methods could
be beneficial for irrigating as much as possible area.
It is really quite difficult to present accurate
estimates of the losses due to shortage of irrigation
water and damages caused by diseases. The losses vary
from year to year and from one region to the other. The
fields have been found to show as much as 100 percent
damage in certain cases. The causes of fluctuations in
production may be many more, but cotton diseases could
not be ignored, neglected and or regretted, because they
also cause variable loss time by time to the crop. It is
becoming obvious that: now, it is up to the cotton
growers and crop protectionists, to design and formulate
ways or mean to combat all enemies of the crop, so that
the losses may be minimized. The causes, symptoms,
preventive and curative control measures of some
important diseases of cotton, are being summarized here
COTTON LEAF CURL VIRUS
Cause: The disease causing virus belongs to Gemini
Symptoms: Upward and downward curling of leaves
accompanied by small as well as main vein thickenings (SVT
as well as MVT) on leaves, pronounced on underside. If a
diseased leaf is viewed from beneath against the light,
thickened vein found darker green and opaque than the
normal. In extreme but not in frequent cases, formation
of the cup shaped or leaf laminar (veins) out growth
called “enation” appears on the back or underside of the
leaf. The newly produced leaves are small, excessively
crinkled and curled at the edge. The primary stem often
tends to grow taller than normal. The enter-nodes being
elongated and irregularly curved but sometimes the whole
plant is stunted. The flowers checked in growth and
become abortive. Bolls remained small in size and failed
to open. All parts of badly hit plants are very brittle
and ready broken.
Transmission: The disease transmitted by feeding of the
white fly, Bemisia tabaci with in 6.5 hours. A single
female, carrying virus, can infest many plants. It may
also be kept in mind that white fly is known to survive
on as many as 53 host plant species, and is responsible
for transmitting 23 crop diseases in region. At global
level, white fly infests 600 different plant species.
Cause: Aspergillus niger, Fusarium oxysporium, Rhizopus
oryzae (belongs to fungi) and a bacterium Xanthomonas
malvacearum reported as predominant causes of boll rot.
Symptoms: The research studies revealed that four
different types of symptoms may occur, which can be
distinguished on the basis of their specific casual
agent, as below:
Black boll or Aspergillus rot: Affected bolls start
losing green color altogether, become pinkish brown and
finally sooty black due to over growth of fungus.
Rhizopus rot: Infected portions become grayish along
with softening of internal tissues. The fungus grows
abundantly and covers many bolls under moist conditions.
Fusarium rot: The bolls become dried with color assuming
reddish and brownish tinge and showing dry and white
fluffy fungal growth inside the bolls on opening.
Bacterial or Xanthomonas rot: Water soaked areas
developed on the bolls giving out gummy substance and
Perpetuation: Diseased plant debris and seeds carry over
the disease causing organisms. Humid conditions after
rain and speedy wind favor the spread and severity of
boll rot. Sometimes, different boll worms also play a
role, to transmit disease, from infected to healthy
bolls or plants.
ANGULAR LEAF SPOT OR BACTERIAL BLIGHT
Cause: A bacterium Xanthomonas malvacearum cause angular
leaf spot or bacterial blight or boll rot of cotton.
Symptoms: The disease attacks all parts of the plant
above ground level, at all stages, causing seedling rot,
angular spots on leaves and stems (sometimes called
black arm disease) and boll rot (as already mentioned).
In initial stages, water soaked lesions (spots) appears
on lower surface of the leaves. Later on, these spots
increase in size, turn brown to black, becoming
necrotic, angular and are visible on the upper surface.
These spots vary in size and then coalesce, forming
irregular patches and giving rise to gummy bacterial
exudates. Heavily infected leaves turn yellow and drop
down. The disease produces elongated black lesions on
the stem, branches and petioles. Stems show cracking and
gummosis (gummy substance) and are easily broken, even
by wind. Bolls are marked by the appearance of water
soaked lesions, which are dark brown to black,
invariably sunken, results in reduced boll size, poor
production of lint and loss in viability in seed.
Perpetuation: Infected seeds and plant debris act as a
source of infection, but can also spread through
irrigation water, rain splashes, wind, insects and
contaminated field implements.
Cause: The fungi Macrophomina phaseolina, Rhizoctonia
spp., Fusarium spp. etc. are predominantly isolated from
Symptoms: The disease affects the roots exclusively,
causing pre-wilt shedding of leaves, yellowing of
foliage, disintegration of root tips, discoloration and
shredding of roots, exudation of drops of smelly liquid
from the rotted plant parts. Mostly, wilting of shoots
occur in only few diseased plants, which ultimately
results in the death of entire plant. This disease
generally appears, when plants are about 4-6 weeks old
and continue up to boll formation. Diseased plants can
be easily pulled out of the soil, appears in patches.
Roots and root-lets show rotting, yellowing,
disintegration and shredding.
Perpetuation: Disease causing fungi are soil borne,
hence it may be claimed that both (fungi and soil)
factors are responsible.
Anthracnose, leaf spots (caused by different fungi),
sooty mold, stenosis, stunting and premature opening of
bolls (Tirak) etc. are also reported to cause disease in
cotton and damage to the crop, which may reduce the
yield, sometimes very low and sometimes so much.
Following disease management practices may help to save
the crop from all above major and minor diseases of
• Cultivation of disease resistant variety is only safe
measure of all different diseases.
• Eradication including collection and burning of plant
debris may help to control seedling, root and boll rots
as well as bacterial blight, because disease inoculum
may also survive through plant debris.
• Deep plowing with short duration, at least two months
before sowing, help to control seedling and root rot.
• Proper land leveling is a preventive measure against
seedling and root rot.
• Use of healthy seed, acid delisting and chemical seed
treatment minimize the disease incidence of seedling,
root and boll rots as well as bacterial blight.
• Crop rotation with non-host i.e. sowing of sorghum for
3 to 4 years is useful for control of seedling and root
• Mixed cropping with kidney bean or fodder and
leguminous crops saves the cotton crop from root rot.
• Proper use of irrigation and chemical fertilizers
improves the disease resistant power in cotton plants.
• Early sowing of crop is preventive measure for control
of boll rot.
• White fly transmits cotton leaf curl virus from
diseased plant to healthy one, whereas, different cotton
boll worms may play a role to transmit the boll rot
diseases, hence white fly and boll worms must be
• Lady’s finger (okra), sun kukra, china rose, thorn
apple (dhatura), mint (podina), karund, cucurbits
(especially water melon), beans, tomatoes, tobacco,
chilies, soy bean, sun flower, cow peas, egg plant (brinjal),
holly hock (gul-e-khera), zinnia, sesame, Ak (Calotropis),
shesham, citrus species etc. are recorded as alternate
host plants of cotton leaf curl virus as well as white
fly, and also some of them are alternate host of boll
worms. Therefore, they all must be eradicated before and
during cotton cropping season. Cotton growing zones may
play a better role for this purpose.
Meanwhile, use of proper cotton production technology as
per recommendations of agricultural experts or
researchers is economical and most effective for cotton
disease management. It is out look and responsibility of
the cotton growers to adopt the modern cotton production
technology and play a role for the development and
prosperity of the country.
Assistant Professor (Plant Pathology), Sindh Agriculture