No doubt '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. 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 be alert.
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 natural 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 AD).
In the midst of the trees no cotton plants are:
So here are no spinners. The empty bazaar
Has ensalted my heart; Foolish girl, in your brain.
Translated by: H.T. Sorely (1938)
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. These diseases
are injurious in some areas, in some years, on some or may be all plant
parts. The magnitude of disease damage depends up on the environment and
cultivar response. The highest (100%) yield losses are reported from the
susceptible/highly susceptible cotton varieties during the presence of
disease causing organisms and favorable environmental conditions.
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 the
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
fungi Macrophomina phaseolina, Rhizoctonia spp., Fusarium spp. etc. are
predominantly isolated from diseased roots.
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.
causing fungi are soil borne, hence it may be claimed that both (fungi
and soil) factors are responsible.
niger, Fusarium oxysporium, Rhizopus oryzae (belongs to fungi) and a
bacterium Xanthomonas malvacearum reported as predominant causes of boll
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 foul
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 bollworms also play a
role, to transmit disease, from infected to healthy bolls or plants.
ANGULAR LEAF SPOT OR BACTERIAL BLIGHT
bacterium Xanthomonas malvacearum cause angular leaf spot or bacterial
blight or boll rot of cotton.
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.
seeds and plant debris act as a source of infection, but can also spread
through irrigation water, rain splashes, wind, insects and contaminated
COTTON LEAF CURL VIRUS
disease-causing virus belongs to Gemini group.
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.
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
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
Following disease management practices may help to
save the crop from all above major and minor diseases of cotton.
*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
*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 minimizes 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 rot.
*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 bollworms may
play a role to transmit the boll rot diseases, hence white fly and
bollworms must be controlled.
*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
outlook 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.