Increased cotton production in BR brings new challenges for research

Brazil is the fifth largest cotton producer in the world and this year took second place in the ranking of the world's largest cotton exporters. This harvest, 2,7 million tons of feather will be produced on Brazilian soil, of which 1,7 million tons will be exported, according to data from Conab. For this leap in national fiber production to be sustainable, it needs to be combined with an increase in the biodiversity of the cultivation system, otherwise it will generate resistance to pests, diseases and weeds, causing the rapid loss of technologies and increasing production costs. This is what the diagnosis carried out by Embrapa researchers and analysts points out. The document, which is part of the Challenges of Brazilian Agribusiness series, provides an x-ray of the current situation of the cotton production chain in Brazil and the world and the main technological challenges for the growth of national production. 

For the general manager of Embrapa Algodão Liv Severino, one of the report's authors, the crop's prospects for the coming years are promising. “On the demand side, the increase in income and population, mainly in Asia, and the global trend towards consumption of natural products, replacing synthetic plastic materials, will boost the consumption of natural fibers. On the supply side, Brazil has the land and technology to meet the increase in global cotton consumption. The quality of the product, advances in methods for controlling pests and tropical diseases, obtaining more productive varieties, the development of efficient production systems and the outstanding organization of the production chain of Brazilian cotton producers are decisive factors in achieving national and international markets”, he assesses.

According to the report, among the main exporters, Brazil is the only country that can grow in productivity and planted area, assuming an increasingly important role in the world cotton market. 

Cotton is the fourth most important crop in Brazilian agriculture, after soybeans, sugar cane and corn. Last year, the Gross Production Value (VBP) was R$34,95 billion, which represents 9,10% in relation to the VBP of crops. In the last three years, the crop has had a spectacular performance, growing 131%. Currently, plume production is concentrated in Mato Grosso, with 64% of the VBP, and 25% in Western Bahia, totaling almost 90% of the value received by producers. Over the last 10 years, average productivity has grown by around 20%, reaching 1.700 kg/ha in the last two harvests.

Technological challenges of tropical agriculture

As it is located in a tropical environment, Brazil has some competitive advantages in relation to producing regions in a temperate environment. One of them is the possibility of economically exploiting the land throughout the year, while in temperate regions agriculture is not very significant in the cold season. Another advantage is the reduced crop cycle that occurs more quickly due to high temperatures.

On the other hand, tropical agriculture has challenges that are not observed in temperate regions. “The intensity and severity of attacks by pests, diseases and weeds are much greater in the tropical environment than in the temperate environment, therefore favoring pests in these conditions, which can cause economic losses to the producer”, points out the report.

With the increase in pests, the number of pesticide applications also increases, and consequently, the resistance of insects, weeds and microorganisms. If a certain fungicide is used intensively to control a disease, after some time there will be a selection of individuals that can resist the fungicide, making it necessary to use another product that has a different mechanism of action to control the disease. The same happens with insects and weeds.

“What we are discovering is that the time to develop this resistance is much shorter in the tropical regions of Brazil when compared to countries with a temperate climate. Cases of resistance take a few decades to be observed in cold regions, while the problem is observed within a few years in tropical agricultural systems in Brazil. The rapid emergence of populations resistant to available inputs and management techniques causes a constant increase in production costs and greater complexity in the production system. This is a constant concern for farmers, because while costs increase every year, the prices of agricultural products do not increase proportionately and the profitability of the activity is threatened”, reveal the researchers.

The solution for the sustainability of Brazilian agriculture comes from lessons taught by nature itself and is being built through the search for increasing biodiversity in production systems. “There is a widely known pattern in the discipline of Ecology called 'Latitudinal diversity gradient' in which species diversity increases according to latitude, with biodiversity being minimum at the poles and maximum at the Equator. Due to this pattern of nature, for an agricultural system to have balance, the number of species in a tropical region needs to be much greater than in an agricultural system located at higher latitudes. The agricultural model initially adopted in Brazil was widely copied from temperate countries, such as the United States, France and Germany. The imported model initially worked, but as soon as problems began to arise, local solutions were developed that are allowing this activity to continue,” says the study.

One of the most important examples of increased biodiversity in cotton crops is the need for crop rotation. “To avoid the uncontrollable increase in the use of pesticides, cotton producers are being forced to increase the number of species cultivated on their crops to keep agricultural systems balanced.”

The crop rotation that began with soybeans and cotton today includes an extensive list of species that are being introduced into Brazilian agricultural systems, including sunn hemp, sorghum, beans, millet, castor beans, several species of grass, stylosans, chickpeas, sesame and many others.

Another example of increasing biodiversity in Brazilian cotton production crops is biological control, which consists of using other species that have the ability to reduce damage caused by pests. For example, wasps that lay eggs inside caterpillars and cause their death, or fungi and viruses that cause diseases in insects.

“The adoption of biological control has been advocated for decades as the least impactful option for the environment and the most sustainable in the long term. However, its adoption is limited because using biological products is much more complex than traditional chemical products. But despite the difficulties, there is growing acceptance of the use of biological control as the main option for maintaining the sustainability of cotton production in Brazil. Examples are emerging on a commercial scale of fungi to control soil nematodes, bacteria to manage insects and wasps or viruses used to control caterpillars, among others”, points out the document.

Threats and solutions for cotton

Among the biggest current threats to cotton production are the boll weevil, ramularia and nematodes. The document presents measures that are being taken by the research to solve the problems. 

The boll weevil is the main pest of cotton and is found in South America. According to the report, the development of technologies for its management needs to be led by Brazil, as the pest is not a priority on other continents. “Weevil management has been carried out with intense use of chemical insecticides and is a source of concern, as insect populations resistant to available insecticides are emerging, increasing production costs and compromising production viability.”

Among the measures being taken to deal with the pest, the destruction of the remains of cotton plants immediately after harvest stands out. You also need to be careful with the plants that grow in the following crops and on the roadsides. “If this control is carried out rigorously, few insects can survive from one year to the next and the intensity of the pest attack remains at low levels.”

A second solution for the boll weevil is being built through a Public Private Partnership between the Brazilian Association of Cotton Producers (Abrapa), the Matogrossense Cotton Institute (IMAmt) and Embrapa. A transgenic variety resistant to the boll weevil is being developed. This variety is expected to be available within 10 years.

Another line of action is biological control of the boll weevil. “Some species of insects (parasitoids) that attack boll weevil larvae are already known and could be used to manage the pest. However, the adoption of this technology in commercial production still requires major technological advances as methods for producing parasitoids on a large scale and at an acceptable cost.” But this solution needs to be associated with the biological control of other pests because if it were necessary to apply insecticides to other pests, the parasitoid released to control the boll weevil would also be affected, eliminating its effect. 

Ramularia spot is the main foliar disease of cotton and, if not adequately controlled, causes economic losses to the producer. Among the main control measures, fungicides and the use of resistant cultivars obtained through genetic improvement stand out. Anticipating that the disease would cause problems in the future, Embrapa began selecting cotton cultivars resistant to ramularia around ten years ago and is currently making varieties resistant to the fungus that causes ramularia available to producers.

Several nematodes attack cotton plants, causing damage that can mean significant losses to production. These microscopic worms feed mainly on the roots, causing various changes to the plants. “It is recommended to use the crop rotation technique to minimize the problem, but accurate diagnoses and appropriate technical guidance are also necessary, as each plant species chosen may be susceptible to a certain nematode and tolerant to others. Therefore, it is necessary to choose exactly which plant species to use in crop rotation so that the result of the technique is satisfactory.”

Embrapa is also developing nematode-resistant cotton varieties and testing crop combinations that enable their management with the adoption of species that offer profitability to the producer and protection to the soil.

Researchers Liv Soares Severino, Sandra Maria Morais Rodrigues, Luiz Gonzaga Chitarra and Elisio Contini and analysts Joaquim Lima Filho, Mierson Mota, Renner Marra and Adalberto Araújo contributed to the development of the diagnosis.