Introduction

Cotton (Gossypium sp.) is one of the most important commercial crops playing a key role in economics. In India cotton is cultivated in 9 million hectares in varied agro-climatic conditions across nine major States. Cotton cultivation offers 200 mandays/ha of employment. It employs directly and indirectly more than 60 million persons in its production, processing and marketing. India has the largest area under cotton, but its production is just 15.8 million bales, much lower for the vast area.

Requirement

• Climate

Cotton is a tropical and subtropical crop. For the successful germination of its seeds, a minimum temperature of 15^o C is required. The optimum temperature range for vegetative growth is 21 ^o - 27 ^o C. It can tolerate temperatures as high as 43 ^oC, but does not do well if the temperature falls below 21 ^oC. During the period of fruiting, warm days and cool nights with large diurnal variations are conducive to good boll and fibre development.

• Soil

In cotton selection on of soil is very important. Cotton is grown on a variety of soils. Soil should be black medium to deep (90cm) having good drainage availability. Cotton does not tolerate water-logging condition. It is grown mainly as a dry crop in the black cotton and medium black soil. Irrigated cotton is taken in the alluvial soils.

Varieties

• Irrigated

D C H-32, J K H Y-1, H-4, H-6, Varlaxmi, Savita, Bikaneri Narma, R S T-9,

R. A. J. H. H-16 (Maru Vikas), F-414, L.H.1556, Ganganagar agethi, H-777, R.S.875, TURAB, H.Y.10, L.R.A.-5166, etc.,

• Rainfed

Y-1, J.L.H-168, L.R.A 5166, P.K.V.Rajat, N H H-44, A H H-468 etc.,

Land preparation

Cotton is sown on ridges and furrows. For irrigated cotton the land is given a deep ploughing followed by two harrowings. Ridges and furrows having different spacing for irrigated and rainfed cotton. For irrigated cotton shallow ridges on 90cm spacing should be prepared which helps in irrigation. According to slope of land, length of ridges should be 6-9m.

Sowing

• Seed treatment

Seed treatment of fungicides should be given @ 3 gram per kg of cotton seed. Also seed treatment with biofertilizers viz. Azobacter, Azospirillum, and Phosphorous Solubilizing Bacteria (PSB) @ 25 gram per kg of seeds. For seed treatment a paste of fungicides/biofertilizer should be prepared enough thick, which cover the seeds and these seeds dried in shade. After completely dried seeds should be used for sowing.

• Spacing

In case of the ridge sown crop hand-dibbling of the seeds at the recommended spacing is commonly followed.

• Irrigated cotton

Hybrid variety (medium soil)- 90x90cm

Deep black soil - 120x90cm

Other varieties- 90x90cm

• Rainfed cotton

Indigenous variety - 45x22.5cm

American variety - 60x30cm

Hybrid varieties - 60x60cm, 75x75cm, 90x90cm

Before sowing soil should be irrigated and after wapsa condition sowing should be done. Small shallow holes should be prepared on middle of the ridge upto 2-3 inch deep and applied recommended fertilizers and 1.0-1.5 gram of thimet and cover it with the soil. On each hill 3-4 cotton seeds should be dibble and cover completely with the soil and apply irrigation immediately. In North and Central India irrigated crop is sown from March-May and rainfed crop in June-July with the commencement of the monsoon. In South India the major portion of the irrigated and rainfed crop is planted in September-October, whereas the sowing of the rainfed crops extended upto November. In Karnataka desi cotton is usually sown in August-September.

Fertilizer

The fertilizer required for irrigated cotton is 100:50:50kg nitrogen, phosphorus and potash per hectare is recommended. The application of nitrogen is given by ring method. 20% nitrogen and whole phosphorus and potash should be given at the time of sowing and 40% nitrogen at the time of square formation and final 40% nitrogen at the time of flowering. In case of rainfed cotton fertilizer dose for desi variety is 50:50:25kg nitrogen, phosphorus and potash per hectare. For hybrid varieties fertilizer dose is 80:40:40 nitrogen, phosphorus and potash per hectare. 1/4 nitrogen and whole phosphorus and potash is given at the time of sowing while 1/2 nitrogen is given 4 weeks after sowing and remaining 1/4 nitrogen is given through spraying.

Irrigation

In case of cotton germination, square initiation, flowering and boll formation and boll development are the critical stages for irrigation. The irrigated cotton crop is mostly sown after a preliminary irrigation and second the light watering is given in three or four days after germination. Subsequent watering depend upon the nature of the soil and the weather conditions. Flowering and boll formation are the critical stages from the point of view of irrigation. The summer sown crop gets frequent irrigations at intervals of 8-12 days. From sowing to square initiation period over irrigation should be avoided to stop the excessive vegetative growth. Skip row method should be followed if there is less availability of water. For first interval of irrigation water should be applied in first, third, fifth row and second interval water should be applied in second, forth and sixth row.

Plant protection

Pest

Jassid and aphids

Nymphs and adults found on the underside of the leaves, sucking the sap; leaves turn yellow and start curling; in severe cases the leaves turn chocolate red and crumple; in such cases, the growth of plant is also stunted.

• Control

Sow resistant varieties; spray the crop fortnightly with 0.02% Phosphamidon, Monocrotophos, Methyl demeton, Dichlorros or Dimethoate, starting with the appearance of the pest; 2-3 sprayings may be necessary.

American Bollworm

Destructive pest, caterpillar borer into square flowers and boll and feed within the boll. While feeding head of caterpillar is inside the square or boll and remaining portion is outside the square and boll.

• Control

When infestation is seen spray following pyrethroids per hectare in 500 litres of water: -

Cypermethrin 25%- 200ml or 10%-500ml or Decamethrin 2.8%- 400ml or 20%- 250ml.

If there is infestation of whitefly and jassids do not spray systemic pyrethroids but spray monocrotophos 830ml in 500 litres of water. Also collect fallen squares, flowers and bolls and burn it immediately. If American bollworm is not controlled after spraying of insecticides, spray Heliothis, NPV 450 L.E. per hectare and collect caterpillars and destroy it.

Red cotton bug

Nymphs and adults suck the sap from the flowers, buds and bolls and taint the lint with faeces. The infested bolls open badly and the quality of the lint is further affected.

• Control

Spray 0.04% Monocrotophos or Quinalphos

Cotton leaf roller

Caterpillars roll the cotton leaves and feed within; exotic varieties are more susceptible; moths, medium sized with yellow wings; active from mid July to September.

• Control

Hand-picking and destruction of rolled leaves with larvae within; spray 0.1% Carbaryl or 0.04% Monocrotophos; repeat, if necessary.

Diseases

Anthracnose

All the above ground parts of the plant are attacked; infection on the seedlings and bolls is serious; large red spots appear on the seedlings; later, they girdle the stem and kill it.

• Control

Treat the seed with any organo-mercurial (Agrosan GN, Ceresan) @ 2-2.5 g/kg; spray the crop with 1% Bordeaux mixture.

Leaf spots

Spots are light brown, circular and numerous, the centre of the spot later turns ashy and falls off, leaving a hole; rusty brown spots of irregular size and shape are observed.

• Control

Spray the crop with 0.3% fixed copper or 0.2% Zineb.

Powdery mildew

White powdery patches appear on the undersurface of the leaves; the corresponding upper portions just above patches become pale and brown.

• Control

Dust the crop with finely powdered sulphur @ 15 kg per hectare.

Intercultural Operations

• Intercropping

During initial stage growth rate of cotton is slow. Therefore it is beneficial to take short duration intercrops. Mainly short duration cereals like black gram, green gram and soyabean is suitable. Intercropping is taken as 2:1 proportion. That is two rows of cotton and one row of intercrop. In irrigated cotton it is beneficial to take groundnut (variety S.B.11 bunch type. In this intercropping, cotton is sown in 1:1 proportion.

• Gap filling

If there is no germination after seven days of sowing and there is gap then fill that gap by dibbling the cotton seeds. Also during thinning fill the gap by planting the cotton plants.

• Thinning

In irrigated cotton at the time of dibbling 3-4 cotton seeds are sown dibbled. Therefore it is necessary to carry out thinning operation after 15-20 days of sowing keeping only two healthy plants at each hill.

• Weeding

Cotton is sensitive for weed growth as weeds compete for water light and nutrients. If there is no control measures of weeds upto 70 days from cotton sowing there is chances of reduction in cotton production due to unsatisfactory growth of cotton crop. Therefore it is essential to keep the field weed free upto 2 months from sowing. To control the weeds 1-2 hand weeding and 2 harrowings should be done.

• Detopping and removal of leaves

In deep black cotton soil due to chemical fertilizer and irrigation there is excessive vegetative growth. Incase of irrigated hybrid cotton due to this there is less boll development and also branches may be break due to weight of bolls. Therefore after 70-80 days removed growing point of main branch is done and leaves of lower branches can be removed alternatively. Due to this there is aeration and bolls not rotten and less incidence of insect and diseases of cotton.

• Use of growth stimulator

To avoid shedding of square, flower and bolls of cotton spraying of napthlaic acetic acid (planofix) @ 1 ml in 4.5 litre soft water should be done at the time of square formation. Second spraying should be carried out 15-20 days after first spraying.

• DAP spraying

At the time of square formation and 30 days after square formation spraying of 2% diammonium phosphate should be carried out for better boll development. For 1 hectare of area 8 kg DAP is used and solution is prepared in 400 litres of water and sprayed.

Harvesting and yield

Cotton is harvested by picking the fully opened bolls. First picking of cotton should be done when 30-35% bolls open fully. Picking should be done early in the morning. At the time of picking first pick clean cotton and then affected cotton. It should be picked separately of different varieties. Second picking should be done 15-20 days after first picking. After picking it should be dried 3-4 days in sun with due care. Cotton should be stored at clean and dry place.

• Irrigated cotton

• Improved varieties- 20-24 quintal per hectare

• Hybrid varieties-25-30 quintal per hectare

• Rainfed cotton

• Desi varieties 8-10 quintal per hectare,

• American variety 11-12 quintal per hectare and

• Hybrid varieties 12-15 quintal per hectare.