Scientists from Brazil and the USA identified two Brazilian strains of Trichoderma that can inhibit up to 100% of the growth of the mold-causing fungus. Also known as Sclerotinia stem rot, white mold is one of the most devastating and limiting diseases that affect cotton and other crops of socioeconomic importance. One of the strains showed good potential to control the mold-causing pathogen under laboratory conditions. The other demonstrated biostimulant effect on cotton growth, due to higher phosphate solubilization in the soil and increased root development. The ideal solution, according to the scientists, is to combine both strains to manage white mold and promote cotton plant growth. A study by scientists from São Paulo State University (Unesp), Embrapa Environment, Federal University of Lavras (Ufla) and the United States Department of Agriculture (USDA) revealed the ability of two Brazilian strains of the Trichoderma fungus - Trichoderma asperelloides CMAA 1584 (BRM 065723) and Trichoderma lentiforme CMAA 1585 (BRM 065775) - to control white mold. It is a highly destructive disease caused by the fungus Sclerotinia sclerotiorum, which attacks several crops of socioeconomic importance to Brazil, such as cotton, soybeans, beans, sunflower and tomatoes, among others. One strain was able to inhibit 100% of the germination of pathogen sclerotia (structures that play an important role in the survival of the fungus from one harvest to another). In addition, both showed an ability to solubilize inorganic phosphorus, a low availability macronutrient in tropical soils. Trichoderma is one of science's main allies in the biological control of agricultural diseases. Microbial products based on this fungus have multifunctional roles in plant protection, such as competition and pathogen parasitism, induction of resistance to diseases, growth stimulation, and increased nutrient availability. It is a strategy that has helped farmers in Brazil and other countries reduce the use of chemical fertilizers and fungicides against white mold, not only in cotton but also in several crops like soybeans and beans Given the importance of this microorganism for global agriculture, scientists have invested in trial studies to identify new Trichoderma strains with potential for biocontrol programs. “In the study in question, the results reinforced the need to select the strain according to the desired target pathogen, taking into account its biology and epidemiology in the cultivation system,” explains the researcher Wagner Bettiol, from Embrapa Environment. According to Bettiol, several strains of Trichoderma fhad been assessed prior to this study, aiming at the control of white mold in bean plants, and those two were the most effective in the tests. The strain Trichoderma asperelloides CMAA 1584 (BRM 065723) showed good potential to control the white mold-causing pathogen under laboratory conditions. The strain Trichoderma lentiforme CMAA 1585 (BRM 065775) demonstrated biostimulant capacity in cotton growth by solubilizing phosphate in the soil and increasing root development. “As the two strains have complementary roles, the suggestion is to combine them to manage white mold and promote cotton plant growth,” says analyst Gabriel Mascarin, from Embrapa Environment. This research is part of the doctoral thesis by Lucas Guedes Silva at Unesp, which generated the paper Dual functionality of Trichoderma: Biocontrol of Sclerotinia sclerotiorum and bioestimulant of cotton plants, published in the journal Frontiers in Plant Science. Importance of cotton in the Brazilian economy Cotton is the most important source of natural fibers in the world. Approximately 150 countries are directly involved in its industrial chain, which generates income for more than 100 million families. Brazil stands out as the fourth largest producer in the world, with about 1.6 million hectares of planted area and production of 6.7 million tons, according to the National Supply Company (Conab). Among several diseases that limit cotton growth and yield, white mold, also known as Sclerotinia stem rot, is one of the most devastating and yield-limiting diseases. “An important aspect of the disease is that in many properties there is a soybean-cotton-soybean crop rotation and both crops are susceptible to the same fungus, annually increasing its incidence,” Bettiol states. White mold causes losses of billions of dollars in harvests and has a major impact on several crops around the world. According to the Brazilian Ministry of Agriculture and Livestock (Mapa), the fungus is considered one of the top eight pests with highest phytosanitary risk for the country, since it poses a serious threat not only to cotton plants at all stages their development, but also to crops of fundamental importance for Brazilian agribusiness, such as soybeans and tomatoes, among others. The pathogen is able to survive for several years in the soil as it produces a resistance structure called sclerodium. Symptoms of white mold in cotton include wilt, necrosis, and rotting of stems, bolls, petioles, and leaves.