BASIC GUIDELINES FOR GROWING COTTON UNDER IRRIGATION AND RAINFED LAND IN SOUTH AFRICA
PERIOD OF GROWTH
The plant cycle stretches over an average of 160 – 180 days, depending on the cultivar planted, the production area and the number of day-degrees (heat units) available for crop development in relation to the planting date. Flowering commences at 70 days post-planting and peaks at 90 – 105 days post-planting. The first bolls form from 90 days onwards, with the first bolls opening on days 115 – 120 post-planting. Most bolls will be open around 120 – 160 days, whereafter harvesting can occur from 160 – 180 days depending on the length of the season for the specific area and the cultivar planted. Development depends on the temperature and heat units/day degrees (dd) available per day. A minimum of 1 300 dd are needed, but preferably around 1 500 dd to ensure mature fibre development.
TEMPERATURE
Cotton requires temperatures above 20°C averages, especially between the flower and boll development phases, but not above 34°C. Temperatures above 36°C can be detrimental to growth. The ideal soil temperature (top 3 cm of soil) for successful germination is 17.5 – 18°C for ten days consistently. Cold spells after planting will influence seed vigour and germination. Minimum temperatures below 15.5°C during boll development will affect fibre quality and yield and cause the plant to cut-out. Plant cut-out starts with temperatures falling below 18°C. Cotton is sensitive to an early frost. The ideal average temperatures, especially during boll development, is 25°C. Historically, the optimal planting time used to be between 15 and 31 October, but planting dates vary per region and should be correlated with the minimum soil temperature, the number of day degrees available for the season. The type of cultivar planted, e.g., a short-seasoned or a long season cultivar, will also influence the planting date.
SUNLIGHT
Full sunshine for 70 – 90% of daylight hours is ideal, with little or no cloudy weather.
MOISTURE
Cotton is a drought-resistant crop because of a well-developed taproot system, longer than 1 m. Regular irrigation is necessary to secure optimal yields. Plant at water field capacity of 100 cm depth, irrigate 15 – 20 cm directly after planting to provide adequate moisture for germination. After germination, no irrigation is necessary for the first three weeks; thereafter, irrigation can be provided weekly. The important periods are early flowering to peak flowering to the first boll formation period. For optimum yields, cotton requires a total of 500 – 650 mm irrigation and rainfall equivalent, depending on region, soil type and climate. Rainfed land requires 300 – 400 mm, depending on soil types and climate. Ideal irrigation intervals will be five days in most cases, evenly distributed during the season. Too much water during flowering and boll development will be detrimental, and intervals bigger than 5 – 7 days between irrigation can cause shedding of squares (contact Cotton SA for more detail on irrigation).
AERIAL MOISTURE
High levels of moisture in the air during boll ripening are detrimental. An open plant canopy is preferred with lower plant populations per hectare. Plant population densities are determined for each region depending on the cultivar planted.
SOIL
Preferably deep, fertile, and well-drained soil is required. Cotton will do well on most soil types. Soil moisture can be determined accurately with a neutron probe or other methods. On sandy soil, smaller amounts of water will be applied at shorter intervals, while on heavier soils, more water can be applied at longer intervals. Cotton is susceptible to over-irrigation yet resistant to soils with relatively high pH but reacts poorly to acidic soils. Ideal soil pH is between 5.5 – 7.5, while ideal soil depth is 800 – 900 mm, or even deeper. The taproot can reach around 1 – 1.2 m.
BEFORE PLANTING
Prepare a fine, even seedbed, take soil samples for fertiliser requirements, and nematode analyses if it is a concern in the area. There is only one registered chemical to control nematodes to be applied postemergence according to the label recommendations. The list of chemicals that are registered for cotton is available on the Agri-Intel website.
FERTILISATION
Fertilise according to the recommendations based on the soil analyses. Avoid over-fertilisation with N (nitrogen). For a yield of 5 tonnes/ha seed cotton, the withdrawal will be approximately N=180 – 250 kg/ha, P=30 – 40 kg/ha and K=80 – 150 kg/ha (total available). Less nitrogen is required on clay soils. Fertilisation should not be applied after eight weeks post-planting. Adapt your fertiliser applications in line with the prediction of your soil analyses, taking into consideration what is in the soil. Often not more than 150 – 180 N is needed not later than peak flowering.
CROP ESTABLISHMENT
Plant when the soil temperature is 17.5°C for ten days and longer. The ideal planting date is usually from late October onwards, while after the 1st to 2nd week in December, potential yields may decrease considerably up to 25%. If the soil is too cold (early planting), germination will be poor. If planting is late, pests at the end of the season will be a problem, and fibre development will not occur successfully. Plant-depth is 20 – 25 mm in heavy soils and 30 mm in sandy soils. Plant more than one seed per plant station to improve vigour to break the soil crust during germination when planted by hand on rainfed fields. Press soil down on planted seed lightly but do not compact soil. Irrigate 15 – 20 mm post-planting before emergence after 5 – 7 days. Rainfed fields need to have 20 – 35 mm of rain before planting in not more than two precipitations.
PLANT POPULATION
Production under irrigated conditions requires a plant population between 70 000 – 88 000 plants/ha, which can vary up to 100 000 plants/ha. High plant populations per hectare provide a closed canopy which is not ideal. Under dryland conditions, the plant populations use to be around 40 000 – 60 000 plants/ha. Producers currently plant between 50 000 – 60 000 plants/ha. Check the cultivar recommendations for the various production regions. Smallholder dryland farming should be in the vicinity of not more than 40 000 plants/ha. Dense plant populations tend to encourage boll rot near the bottom of the plant as a result of fungal infections secondary to insect damage.
SPACING
Between row spacing of 91 – 100 cm, with interplant spacing around 15 – 20 cm for irrigated cotton, to accommodate the different mechanical harvesting processes. Farmers should make sure what kind of mechanical harvesting processes will be used. Production under dryland conditions commonly makes use of double skip-rows with a 91 cm inter-row spacing so-called tramlines. Row spacing for dryland practices varies from full rows to single-skip to double-skip rows to conserve soil moisture.
GROWTH REGULATORS
Growth regulators, i.e., mepikwat chloride, is necessary to limit vigorous growth and allow nutrient flow to bolls. The first bolls closest to the stem contribute 70 – 80% to the yield. Maximum plant height should not exceed 700 – 800 mm and need to be controlled by at least 2 – 3 dosages of a registered growth regulator. Spray at cotton cut-out when the last white flower, closest to the stem, is about 5 – 6 nodes from the plant top. The short season variety Candia has a short compact growth pattern and rarely requires spraying. Growth should, however, be monitored weekly, not to exceed more than 7.1 mm per week as in the case with other cultivars Cotton can grow vigorously under irrigation with the addition of fertiliser and during high rainfall periods. Plant height and internode length should be monitored weekly to decide on when to spray.
DEFOLIATING
Defoliation is necessary for mechanical harvesting to obtain a high grade and good fibre characteristics. Refer to the list of registered products recommended by CropLife, on their Agri-Intel website, for defoliation products registered on cotton.
SEED COTTON YIELD
Average yields obtained under irrigation with current Bt-varieties should be approximately 3.6 – 5 tonnes/ha, or sometimes even more. Under dryland conditions, 1.2 – 2 tonnes/ha can be expected. Dryland areas that are carefully managed with modern techniques as precision farming can result in even higher yields. The potential for dryland production in South Africa lies in the expansion of hectarages, especially in areas where there is a water table. Current technologies make cotton more adaptable and profitable to cultivate in dryland areas in comparison with other crops. Seed cotton can be harvested by hand or machine. A spindle picker can harvest approximately 900 ha during the season, while a stripper can harvest around 1 200 ha per season, depending on the yields per hectare. Strippers are usually used for dryland farming when lower yields are obtained. A spindle picker, 6-row configuration, is more effective on irrigated cotton when a higher yield is expected. Handpicking is usually practised by small-scale farmers and calculated at a picking rate of around 30 – 35 kg per day per person.
PESTS
Early-season pests include various thrips on seedlings, aphids, the Cotton stem weevil (Apion, in some areas), the Black cotton beetle (Syagrus, some areas); Mid-season pests like the bollworm complex especially on refugia, leafhoppers (Jassidae); whitefly, sometimes the Red spider mite, but rarely mealybugs. Late-season pests include the Green Vegetable stink bug, the “Mirid-bug”, Cotton stainers and Dusky cotton stainers. Avoid unregistered products and repetitive spraying of pyrethroids, carbamates and any organophosphates. Follow an Integrated Pest Management approach by scouting 24 plants per field weekly from the 4-leaf stage. It is crucial to note that no alternative pesticides other than those specifically approved for South African cotton may be used, be they synthetic chemical products or biological products. Contact Cotton SA to obtain thresholds for the various pests. Current stackgene Bt-technologies provide adequate bollworm control, but cotton should still be scouted to make sure of pest populations and to monitor secondary pests.
All cotton seed of cultivars planted in South Africa expresses bollworm resistance due to two Bt-genes in stackgene formation (Bollgard 2™) combined with herbicide tolerance, expressed by the Roundup Ready Flex™ trait, with glyphosate resistance. Seed treatments are applied to seed to provide protection against early-season sucking pests, like thrips, aphids, and leafhoppers, and against some fungal diseases. The cultivars that are planted include DP1541 BG2RRF, DP1531 BG2RRF, DP1240 BG2RRF, Candia BG2RRF and PM3225 BG2RRF (Paymaster). The latter is a hairy cultivar, while all others have smooth leaf surfaces.
The refuge area must be planted with Delta 18RRF, which is a non-Bt cultivar. Please note that there is a license agreement that producers must sign, which also explains the options the producer has to plant the refugia.
Cotton cultivar recommendations are made by the Technical Committee of Cotton SA in conjunction with experts in the cotton industry. The cultivars recommended for the different areas are registered for planting in the RSA. In compiling the recommendations, the following aspects are taken into consideration:
• Yield
• Fibre length
• Fibre strength
• Micronaire
• Fibre percentage
• Good adaptability and tolerance to disease
• Cultivars with acceptable potential
• Planting dates for each cultivar
• Optimal plant population per cultivar
Cotton research is funded by the income derived from a statutory levy received from the gin on each bale of lint produced. Research is facilitated by the Technical Manager, following suggestions for projects from the industry, the available budget and further evaluation by the Technical Subcommittee and the Technical Research Committee of Cotton SA. Final evaluation and recommendations are formulated by the South African Cotton Producers Organisation (SACPO), whereafter they are submitted to the Board of Cotton SA for approval. Research projects are evaluated annually during the regional SACPO meetings held before each season. Role-players are identified to assist with the research in the industry. Role-players include the gins, contracted service providers, the (Agriculture Research Council) ARC and farmers.
Large donations of seed are often made by some of the gins, sometimes by seed suppliers or individual farmers, for the planting of trials.Smallholder dryland demonstration trials are often done in specific areas, to demonstrate what production methods are most preferable.
ACCESS TO NEW TECHNOLOGY
Third-generation technology, with the Bollgard 3™ trait, will provide the producer with bollworm control through the expression of three Bt- proteins. Multiple gene exposure will ensure that bollworms will not develop resistance against the technology, should refuge requirements be met. Various new technologies are available that also include herbicide-tolerant traits to provide tolerance to either glyphosate and gluphosinate or in combinations with 2.4 D or dicamba. Having access to any, all, or a combination of these technologies would enable producers to combat herbicide-resistant weeds while having access to cotton that expresses bollworm resistance. Third-generation technologies are not yet available in South Africa.
SEED SECURITY
Access to quality seeds is one of the most important factors for the producer. The availability of alternative plant genetics, especially those adapted to dryland conditions, is critical to dryland farmers to ensure financially viable farming. The South African Cottonseed Growers-NPC (SACG-NPC) has been established to facilitate seed security and manage the challenges and research around the availability of suitable cultivars for specific areas in South Africa. This company aims to investigate long-term seed alternatives with new plant genetic material that include the added benefit of new technologies, best suited for South African conditions.
INTEGRATED FIBRE MANAGEMENT FORUM
The Integrated Fibre Management Forum was launched in August 2020 to benchmark the South African crop to international cotton spinners’ requirements to secure markets for South African lint. Along with seed security, cotton production management strategies remain important contributing factors towards yielding a successful crop. Focused messages, aligned with the seasonal production cycle of cotton, containing important facts that can influence fibre formation from the pre-planting phase right through to the ginning stage, are distributed to the farmers.
Annual research reports contain the summarised feedback on the various research projects conducted for the past season, may be downloaded here:
BASIC GUIDELINES FOR GROWING COTTON UNDER IRRIGATION AND RAINFED LAND IN SOUTH AFRICA
PERIOD OF GROWTH
The plant cycle stretches over an average of 160 – 180 days, depending on the cultivar planted, the production area and the number of day-degrees (heat units) available for crop development in relation to the planting date. Flowering commences at 70 days post-planting and peaks at 90 – 105 days post-planting. The first bolls form from 90 days onwards, with the first bolls opening on days 115 – 120 post-planting. Most bolls will be open around 120 – 160 days, whereafter harvesting can occur from 160 – 180 days depending on the length of the season for the specific area and the cultivar planted. Development depends on the temperature and heat units/day degrees (dd) available per day. A minimum of 1 300 dd are needed, but preferably around 1 500 dd to ensure mature fibre development.
TEMPERATURE
Cotton requires temperatures above 20°C averages, especially between the flower and boll development phases, but not above 34°C. Temperatures above 36°C can be detrimental to growth. The ideal soil temperature (top 3 cm of soil) for successful germination is 17.5 – 18°C for ten days consistently. Cold spells after planting will influence seed vigour and germination. Minimum temperatures below 15.5°C during boll development will affect fibre quality and yield and cause the plant to cut-out. Plant cut-out starts with temperatures falling below 18°C. Cotton is sensitive to an early frost. The ideal average temperatures, especially during boll development, is 25°C. Historically, the optimal planting time used to be between 15 and 31 October, but planting dates vary per region and should be correlated with the minimum soil temperature, the number of day degrees available for the season. The type of cultivar planted, e.g., a short-seasoned or a long season cultivar will also influence the planting date.
SUNLIGHT
Full sunshine for 70 – 90% of daylight hours is ideal, with little or no cloudy weather.
MOISTURE
Cotton is a drought-resistant crop because of a well-developed taproot system, longer than 1 m. Regular irrigation is necessary to secure optimal yields. Plant at water field capacity of 100 cm depth, irrigate 15 – 20 cm directly after planting to provide adequate moisture for germination. After germination, no irrigation is necessary for the first three weeks; thereafter, irrigation can be provided weekly. The important periods are early flowering to peak flowering to the first boll formation period. For optimum yields, cotton requires a total of 500 – 650 mm irrigation and rainfall equivalent, depending on region, soil type and climate. Rainfed land requires 300 – 400 mm, depending on soil types and climate. Ideal irrigation intervals will be five days in most cases, evenly distributed during the season. Too much water during flowering and boll development will be detrimental, and intervals bigger than 5 – 7 days between irrigation can cause shedding of squares (contact Cotton SA for more detail on irrigation).
AERIAL MOISTURE
High levels of moisture in the air during boll ripening are detrimental. An open plant canopy is preferred with lower plant populations per hectare. Plant population densities are determined for each region depending on the cultivar planted.
SOIL
Preferably deep, fertile, and well-drained soil is required. Cotton will do well on most soil types. Soil moisture can be determined accurately with a neutron probe or other methods. On sandy soil, smaller amounts of water will be applied at shorter intervals, while on heavier soils, more water can be applied at longer intervals. Cotton is susceptible to over-irrigation yet resistant to soils with relatively high pH but reacts poorly to acidic soils. Ideal soil pH is between 5.5 – 7.5, while ideal soil depth is 800 – 900 mm, or even deeper. The taproot can reach around 1 – 1.2 m.
BEFORE PLANTING
Prepare a fine, even seedbed, take soil samples for fertiliser requirements, and nematode analyses if it is a concern in the area. There is only one registered chemical to control nematodes to be applied postemergence according to the label recommendations. The list of chemicals that are registered for cotton is available on the Agri-Intel website.
FERTILISATION
Fertilise according to the recommendations based on the soil analyses. Avoid over-fertilisation with N (nitrogen). For a yield of 5 tonnes/ha seed cotton, the withdrawal will be approximately N=180 – 250 kg/ha, P=30 – 40 kg/ha and K=80 – 150 kg/ha (total available). Less nitrogen is required on clay soils. Fertilisation should not be applied after eight weeks post-planting. Adapt your fertiliser applications in line with the prediction of your soil analyses, taking into consideration what is in the soil. Often not more than 150 – 180 N is needed not later than peak flowering.
CROP ESTABLISHMENT
Plant when the soil temperature is 17.5°C for ten days and longer. The ideal planting date is usually from late October onwards, while after the 1st to 2nd week in December, potential yields may decrease considerably up to 25%. If the soil is too cold (early planting), germination will be poor. If planting is late, pests at the end of the season will be a problem, and fibre development will not occur successfully. Plant-depth is 20 – 25 mm in heavy soils and 30 mm in sandy soils. Plant more than one seed per plant station to improve vigour to break the soil crust during germination when planted by hand on rainfed fields. Press soil down on planted seed lightly but do not compact soil. Irrigate 15 – 20 mm post-planting before emergence after 5 – 7 days. Rainfed fields need to have 20 – 35 mm of rain before planting in not more than two precipitations.
PLANT POPULATION
Production under irrigated conditions requires a plant population between 70 000 – 88 000 plants/ha, which can vary up to 100 000 plants/ha. High plant populations per hectare provide a closed canopy which is not ideal. Under dryland conditions, the plant populations use to be around 40 000 – 60 000 plants/ha. Producers currently plant between 50 000 – 60 000 plants/ha. Check the cultivar recommendations for the various production regions. Smallholder dryland farming should be in the vicinity of not more than 40 000 plants/ha. Dense plant populations tend to encourage boll rot near the bottom of the plant as a result of fungal infections secondary to insect damage.
SPACING
Between row spacing of 91 – 100 cm, with interplant spacing around 15 – 20 cm for irrigated cotton, to accommodate the different mechanical harvesting processes. Farmers should make sure what kind of mechanical harvesting processes will be used. Production under dryland conditions commonly makes use of double skip-rows with a 91 cm inter-row spacing so-called tramlines. Row spacing for dryland practices varies from full rows to single-skip to double-skip rows to conserve soil moisture.
GROWTH REGULATORS
Growth regulators, i.e., mepikwat chloride, is necessary to limit vigorous growth and allow nutrient flow to bolls. The first bolls closest to the stem contribute 70 – 80% to the yield. Maximum plant height should not exceed 700 – 800 mm and need to be controlled by at least 2 – 3 dosages of a registered growth regulator. Spray at cotton cut-out when the last white flower, closest to the stem, is about 5 – 6 nodes from the plant top. The short season variety Candia has a short compact growth pattern and rarely requires spraying. Growth should, however, be monitored weekly, not to exceed more than 7.1 mm per week as in the case with other cultivars Cotton can grow vigorously under irrigation with the addition of fertiliser and during high rainfall periods. Plant height and internode length should be monitored weekly to decide on when to spray.
DEFOLIATING
Defoliation is necessary for mechanical harvesting to obtain a high grade and good fibre characteristics. Refer to the list of registered products recommended by CropLife, on their Agri-Intel website, for defoliation products registered on cotton.
SEED COTTON YIELD
Average yields obtained under irrigation with current Bt-varieties should be approximately 3.6 – 5 tonnes/ha, or sometimes even more. Under dryland conditions, 1.2 – 2 tonnes/ha can be expected. Dryland areas that are carefully managed with modern techniques as precision farming can result in even higher yields. The potential for dryland production in South Africa lies in the expansion of hectarages, especially in areas where there is a water table. Current technologies make cotton more adaptable and profitable to cultivate in dryland areas in comparison with other crops. Seed cotton can be harvested by hand or machine. A spindle picker can harvest approximately 900 ha during the season, while a stripper can harvest around 1 200 ha per season, depending on the yields per hectare. Strippers are usually used for dryland farming when lower yields are obtained. A spindle picker, 6-row configuration, is more effective on irrigated cotton when a higher yield is expected. Handpicking is usually practised by small-scale farmers and calculated at a picking rate of around 30 – 35 kg per day per person.
PESTS
Early-season pests include various thrips on seedlings, aphids, the Cotton stem weevil (Apion, in some areas), the Black cotton beetle (Syagrus, some areas); Mid-season pests like the bollworm complex especially on refugia, leafhoppers (Jassidae); whitefly, sometimes the Red spider mite, but rarely mealybugs. Late-season pests include the Green Vegetable stink bug, the “Mirid-bug”, Cotton stainers and Dusky cotton stainers. Avoid unregistered products and repetitive spraying of pyrethroids, carbamates and any organophosphates. Follow an Integrated Pest Management approach by scouting 24 plants per field weekly from the 4-leaf stage. It is crucial to note that no alternative pesticides other than those specifically approved for South African cotton may be used, be they synthetic chemical products or biological products. Contact Cotton SA to obtain thresholds for the various pests. Current stackgene Bt-technologies provide adequate bollworm control, but cotton should still be scouted to make sure of pest populations and to monitor secondary pests.
All cultivars planted in South Africa have the Bt-gene, which exhibits bollworm resistance combined with the Roundup Ready Flex ®, with glyphosate resistance. Seed treatments protect against early-season sucking pests, like thrips, aphids and leafhoppers, and against diseases. The cultivars that are planted include DP1541, DP1531, DP1240, Candia and MP3225 (Paymaster). The latter is a hairy cultivar, while all others have smooth leaf surfaces.
The refuge area is planted with DP18RF, which is a non-Bt cultivar. Please note the license agreement that producers must sign for an explanation of the refugia.
Cotton cultivar recommendations are made by the Technical Committee of Cotton SA in conjunction with experts in the cotton industry. The cultivars recommended for the different areas are registered for planting in the RSA. In compiling the recommendations, the following aspects are taken into consideration:
• Yield
• Fibre length
• Fibre strength
• Micronaire
• Fibre percentage
• Good adaptability and tolerance to disease
• Cultivars with acceptable potential
• Planting dates for each cultivar
• Optimal plant population per cultivar
Cotton research is funded by the income derived from a statutory levy received from the gin on each bale of lint produced. Research is facilitated by the Technical Manager, following suggestions for projects from the industry, the available budget and further evaluation by the Technical Subcommittee and the Technical Research Committee of Cotton SA. Final evaluation and recommendations are formulated by the South African Cotton Producers Organisation (SACPO), whereafter they are submitted to the Board of Cotton SA for approval. Research projects are evaluated annually during the regional SACPO meetings held before each season. Role-players are identified to assist with the research in the industry. Role-players include the gins, contracted service providers, the (Agriculture Research Council) ARC and farmers.
Large donations of seed are often made by some of the gins, sometimes by seed suppliers or individual farmers, for the planting of trials.Smallholder dryland demonstration trials are often done in specific areas, to demonstrate what production methods are most preferable.
ACCESS TO NEW TECHNOLOGY
Third-generation technology will provide the producer with bollworm control through the expression of three proteins. Multiple gene exposure will ensure that bollworms will not develop resistance against the technology, should refuge requirements be met. New technologies also include herbicide-tolerant traits to provide tolerance to glyphosate, glyphosinate and dicamba. Having access to any, all, or a combination of these technologies in alternative varieties would enable producers to combat herbicide-resistant weeds, while having access to cotton that expresses bollworm resistance. Third-generation technologies are not yet available in South Africa.
SEED SECURITY
Seed security, with the quality of the seed, are the most important factors for the producer. The availability of alternative plant genetics, especially those adapted to dryland conditions is critical to dryland farmers to ensure financially viable farming. The South African Cottonseed Growers-NPC (SACG-NPC) has been established to facilitate seed security and manage the challenges and research around the availability of suitable cultivars for specific areas in South Africa. This company aims to investigate long-term seed alternatives with new plant genetic material that include the added benefit of new technologies, best suited for South African conditions.
INTEGRATED FIBRE MANAGEMENT FORUM
The Integrated Fibre Management Forum was launched in August 2020 to benchmark the South African crop to international cotton spinners requirements to secure markets for South African lint. Along with seed security, cotton production management strategies remain important contributing factors towards yielding a successful crop. Focused messages, aligned with the seasonal production cycle of cotton, containing important facts that can influence fibre formation from the pre-planning phase right through to the ginning phase, are distributed to the farmers.
Annual research reports contain the summarised feedback on the various research projects conducted for the past season, may be downloaded here:
Research Projects
- Minimum Input Production System.
- High-Temperature Tolerance in Cotton.
- Evaluation of the Effect of Planting Date on Production, Fibre Quality and Colour of Cotton Cultivars Produced in South Africa.
- Evaluation of the Effect of Biological Control Products or Environmentally-friendly Products for the Management of Nematodes in a Cotton Farming System.
- Survey of the Current Status of Disease and Pests on Cotton in SA.