Uso de Bacillus subtilis no manejo de fitonematoides e efeito da solarização sobre Pratylenchus coffeae em mudas de bananeira

Abstract

The low productivity and quality of Brazilian bananas are largely attributed to plant diseases caused by biotic factors, like nematodes, fungi, bacteria and viruses. Plant-parasitic nematodes cause damage on banana roots and rhizomes, reducing the ability for water uptake and nutrient absorption from the soil and triggering poor anchoring, that may cause toppling symptoms. Among the recommended techniques used for controlling nematodes are the use of organic matter and plant extracts with nematicidal properties, flooding, fallowing, crop rotation, use of resistant cultivars, nematicides, heat treatment and biological control. The aim of this work was to investigate the effects of the bionematicide Nemathel® (Bacillus subtilis) and solarization on banana rhizome seedlings infected with plant parasitic nematodes. In a first experiment, infected seedlings were dipped for 30 minutes in Nemathel® at 50, 100, 150, 200 and 250 mL/10 L water plus the positive (Carbofurano) and negative (water) controls. A second experiment was performed outdoors with infected rhizomes wrapped within two layers of clear plastic bags and exposed to sunlight for 0, 2, 6 and 8 h. The air temperatures of the area were recorded as well as the rhizome temperatures were registered by automatic and continuous measurement using a PROB-107 sensor. After solar exposition, the infected rhizomes were grown in pots containing sterilized soil in a greenhouse. The experiments were evaluated four and three months after the treatment application, respectively. The percentage of rhizome sprouting and nematode populations in the soil, rhizome and roots were recorded. The results showed that dosages of 200 and 250 mL of the bionematicide Nemathel®)/10 L water, and periods of 6 and 8 hours of rhizome exposition to sunlight promoted the largest reduction in nematode populations.