ABOUT COTTON PRODUCTION

Of key importance in cotton production is the ability to convert available resources (which are limited in most cases) into a high yielding and good quality product. Yield itself is determined by two distinct aspects, that is number of bolls and the weight of the boll. In order to achieve this, a grower needs to emphasis on factors that are conducive in achieving the two distinct aspects.



 

    Introduction

    Of key importance in cotton production is the ability to convert available resources (which are limited in most cases) into a high yielding and good quality product. Yield itself is determined by two distinct aspects, that is number of bolls and the weight of the boll. In order to achieve this, a grower needs to emphasis on factors that are conducive in achieving the two distinct aspects.

    Key Areas to Focus On:

    Establishing The Crop.

    • Cotton is a long season crop taking up to 120 days from the day of planting to the day of ready for market. It should therefore be established as early in the season as possible.
    • In Zimbabwe cotton planting is guided by legislation, stipulating that by the 5th of October each year, growers in the Lowveld should be establishing the crop while those in the Middle-veld can do so by the 20th of October each year.
    • Achieving evenness in the crop stand and the right plant population is key to increased productivity.
    • The general recommendation is 100cm inter-row and 30cm in-row translating to a plant population of 33 333 plants per ha.

    Nutrition

    • Soil analysis is important in determining the amount and type of fertilizer that should be applied to cotton for maximum yield levels.
    • Fertilizer application rates vary according to soil fertility & types, with heavy soils requiring less fertilizer and increases quantities of both basal and top dressing fertilizers higher in looser soil types, see table 1 below.
    • Table 1: Fertilizers Application rates according to natural soil fertility

      FERTILIZER REQUIREMENTS(KG/HA) HEAVY SOILS MEDIUM SOILS POOR SOILS
      Compound L 200-250 250-300 300-400
      Ammonium Nitrate 0-50 50-100 100-150
      Urea 0-40 40-75 75-120
    • Accurate timing of fertilizer application is a fundamental element. Basal Fertilizer has to be during planting while top dressing is done between 6-10 weeks after planting.

    PEST AND DISEASE CONTROL

    • Integrated Pest Management will ensure good quality and high yielding cotton crop.
    • To avoid Pest and disease build up and carry over into the next season, growers of cotton should slash cotton stalks and burn them as legislated. This is to be done by the 15th of August each year for the Lowveld and by the 10th of September of each year for the rest of the country.
    • Cotton is affected by a number of pests& Diseases and effect pest and disease control is hinged on the key element of scouting which should commence 4 weeks after the crop has emerged.
    • Common Cotton pests can be divided into three main groups which are :
      • o Bollworms-Pink bollworm, Red bollworm, American Bollworm
        o Leaf Eaters – Cotton looper, Cotton Leaf worm, fall armyworm
        o Sucking pests- Cotton Mealy bug , Cotton Aphids, Jassids, Red Spider mite ,White Fly ,Cotton Stainers

      BOLLWORMS

      1. Pink Bollworm: Pectinophora gossypiella

      Is a major chewing insect of cotton crop.

      Symptoms of damage include the following:

    • Rosetted flowers
    • The holes of entry plugged by excreta of larvae which are feeding inside kernels.
    • The cut window holes (interlobular burrowing) in the two adjoining seeds thereby forming “double seeds”
    • The attacked bud and immature bolls drop off
    • Failure of buds to open, fruit shedding ,lint damage ,discoloured and seed loss
    • 2. Red Bollworm: Diparopsis castanea

      Symptoms of damage include the following:

    • Bolls show irregular bore holes and red coloured larvae
    • Drying and falling of immature squares and immature bolls
    • 3. American Bollworm: Heliothis Armigera

      Symptoms of damage include the following:

    • Dropping ,withered and drying tender shoots
    • Flared up squares in plants
    • Shed squares and small bolls with bore holes
    • Rosette flowers in plants
    • Bolls with entrance hole plugged with excreta
    • Matured bolls not properly opening
    • LEAF EATERS

      1. Cotton looper : Anomis flava

      Symptoms of damage include the following:

    • Loopers are leaf feeders and prefer older leaves hence infestation results in leaf defoliation from bottom upwards.
    • 2. Cotton Leaf worm : Spodoptera Littoralis

      Symptoms of damage include the following:

    • Larvae feed on leaves creating large holes of irregular sharp and all that remains are bigger veins.
    • Shedding and drying up of the bud or young boll after the larvae bores inside the boll consuming the whole contents.
    • 3. Fall Armyworm: Spodoptera Frugiperda

      Feeds on leaves and fruiting structure of a cotton plant

      Symptoms of damage include the following:

    • Defoliation
    • Cut off branches and stalks
    • SUCKING PESTS

      1. Mealy Bugs: Phenacoccus sp., Ferrisa sp. and Macenellicoccus sp

      These feed on plant juices and act as a vector of various diseases.

      Symptoms of damage include the following:

    • Heavy Clustering of mealy bugs usually seen under the surface of leaves as thick mat wit waxy secretion
    • Excrete copius amount of honey due on which the fungus sooty mould grow
    • Affected plants appear sick and black ,resulting in reduced fruiting capacity
    • 2. Cotton Aphids: Aphis gossypii

      Symptoms of damage include the following:

    • Infesting tender shoots and under surface of the leaves
    • Curling and crinkling of leaves
    • Stunted growth
    • Blighted appearance when infection is severe
    • Development of black sooty mould due to excretion of honey dew giving the plant a dark appearance.
    • 3. White Fly : Bemisia Tabaci

      Symptoms of damage include the following:

    • Chorotic Spots on the leaves which latter coalesce forming irregular.
    • Yellowing of leaf tissue which extends from veins to the outer edges of the leaves
    • Severe infestation results in premature defoliation
    • Development of sooty mould
    • Shedding of buds and bolls and poor boll opening
    • Also transmits the leaf curl virus diseases of cotton
    • 4. Cotton strainers/Red cotton bug : Dysdercus cingulantus

      Symptoms of damage include the following:

    • Red stained lint and rotting bolls
    • Inner boll wall with warty growth or water soaked spots
    • Young bolls abort and turn dark brown
    • 5. Two-spotted Spider Mite : Tetranychus urticae

      Symptoms of damage include the following:

    • Bronzing of the upper leaf surface near the petiole or leaf fold.
    • Heavy infestation turns the leaf red and becomes covered with fine webbing and affected leaf dries and falls off.
    • 6. Cotton Jassids (Leafhoppers): Amrasca terraereginae

      Symptoms of damage include the following:

    • Tender leaves become yellow
    • The margins of the leaves start curling downwards and reddening sets in
    • In the case of severe infestation ,leaves get a bronze or brick red colour which is typical “hopper burn” symptom
    • The margins of the leaves get broken and crumble into pierces when crushed
    • The leaves dry up and are shed and the growth of the crop is retarded
    • Transmit diseases such as viruses and mycoplasma

  • To avoid or minimise pests from developing chemical resistance build-up it is important to observe a chemical rotational regime which changes after every two years in Zimbabwe.
  • All chemicals are to be handled with caution and empty containers to be disposed of in an environmental friendly manner.
  • WEED CONTROL

  • Weed control is of utmost importance in cotton production and the presence of weeds in a cotton field will have serious negative impacts on yield levels considering the fact that weeds tend to compete with the cotton crop for light, water and nutrients.
  • From emergency to harvesting the cotton field should be kept free from weeds.
  • PICKING

  • Seed cotton picking should start when an average of 3-4 bolls per plant split.
  • During picking two bags are to be used to allow pre-grading.