Biocontrol Potential of Trichoderma and Bacillus Species on Fusarium oxysporum f. sp vasinfectum

Fusarium wilt, caused by Fusarium oxysporum f. sp. vasinfectum, is one of the major diseases of cotton. Preventive methods to manage this disease should be adopted what includes the seed treatment with biocontrol agents as a good alternative. This work aimed to evaluate the efficiency of biological products based on Trichoderma spp. and Bacillus subtilis in the control of Fusarium oxysporum f. sp. vasinfectum (Fov) applied in seeds and seedlings of cotton. The experiment was carried out at the Laboratorio de Fitopatologia of the Centro de Ciencias Agrarias, of the Universidade Federal de Paraiba (CCA-UFPB), located in the city of Areia, Paraiba - Brazil. The disease transmission of the seeds to the seedlings was evaluated. After the transmission test, cotton seeds of the variety Moco (Gossypium hirsutum var. Marie-gallante (Watt) Hutch.), BRS 286 and Topazio cultivar (Gossypium hirsutum L.) were submitted to the treatments T1 - Control, T2 - Trichodel® (0,5 mL); T3-Trichodel® (1.0 mL); T4-Trichodel® (1.5 mL); T5-Trichodel® (2.0 mL); T6- Bactel® (2.0 mL); T7-Bactel® (2.5 mL); T8-Bactel® (3.0 mL); T9-Bactel® (3.5 mL) diluted in 100 mL SDW; T10 - Fungicide Captana (240 g / 100 kg of seeds) and inoculated with Fov. The pathogen incidence of the seeds was evaluated seven days after the inoculation (DAI). To evaluate the biological control of Fov in the seedlings, the treated seeds were submitted to the following inoculation methods: 1 - inoculation of the substrate with a pathogen conidia suspension; 2 - immersion of the seeds in the conidia suspension and 3 - direct contact of the seeds with the pathogen mycelium. Twenty-one DAI the disease severity and percentage of seedlings with vascular darkening were evaluated. It was observed a transmission rate of 64.0 to 89.0% of the seeds to the seedlings. Trichodel® reduced the incidence and severity of Fov in the cotton seedlings and was the most efficient product.