Associação de Pochonia chlamydosporia e subproduto sólido da indústria vinícola no controle de Meloidogyne javanica

Abstract

The biological control and the addition of organic matter to the soil represent the main alternatives for the control of root-knot nematode. The objectives of this study were to evaluate the effect of solid wine industry by-product (SSIV) on the development, in vitro, of Pochonia chlamydosporia and the effect of combining this fungus with the SSIV on the management of Meloidogyne javanica in tomatoes grown in a greenhouse. To evaluate the direct effect of the SSIV on fungal development, concentrations (0, 5, 10, and 15%) of the aqueous SSIV extract were applied to potato-dextrose-agar (BDA) culture medium. The mixture was then poured into Petri dishes and a disk of 'Corn Meal Agar' (CMA) culture medium colonized by the fungus was placed in the centre of each plate. A further study evaluated the effect of volatile SSIV compounds on the development of P. chlamydosporia. For this, twopart Petri dishes were utilised, to one of the compartments the concentrations of SSIV (0.000, 0.065, 0.125, 0.250, and 0.500 g plate-1) and 2 mL plate-1 sterile distilled water were added. To the other compartment, which contained BDA culture medium, a disc of CMA culture medium colonised by the fungus was added in the centre. The plates from the two studies were stored in a growth chamber in the dark at 21 °C. The two studies were performed twice. After 14 days, the diameter of the colonies and the production of fungal conidia were evaluated. The SSIV reduced fungal growth by 9 to 21% in the two studies, and reduced conidia production in the first study. In the greenhouse, the combination of SSIV (30 g kg-1 of substrate) with the concentrations of P. chlamydosporia with chlamydospores (500; 1,500; 2,500; 3,500; 4,500; and 5,000 chlamydospores g-1 of substrate) or without chlamydospores (2.5, 5, 10, and 15 g of inoculum of fungus kg-1 substrate) were evaluated. Three treatments were used as controls in each assay: the addition of P. chlamydosporia (5,000 chlamydospores g-1 substrate or 15 g of inoculum of fungus kg-1 of substrate), the addition of SSIV (30 g SSIV kg-1 of substrate) and only substrate. Following this, each bag containing 4 kg of sterilised substrate and the respective treatments were infested with 6,000 M. javanica eggs kg-1 of substrate, homogenized, moistened until 60% of field capacity and then stored for 14 days in the dark at 25 °C. The substrate was then transferred to 500 ml polypropylene pots, and one tomato seeding was transplanted into each pot. After 60 days the height, the shoot and fresh root masses, and the numbers of nematode galls and eggs were evaluated. The combination of SSIV and the fungus, independent of the type of fungal inoculum, increased the development of the tomato plants and the control of the nematodes. The fungal concentrations most recommended to combine with the SSIV were 3,500 chlamydospores g-1 of substrate and 15 g of inoculum without chlamydospores kg-1 of substrate, because, besides controlling effectively the nematode, they also improved the development of the tomato plants. It was concluded that the combination of SSIV and the fungus P. chlamydosporia improves the management of this root-knot nematode.