Influence of aqueous extracts of black angico on Pratylenchus brachyurus in cotton plants

Abstract

The root lesion nematode (Pratylenchus brachyurus) is one of the main phytosanitary problems of cotton plants in Brazil. Searching for alternatives that minimize the damages in the crop, several methods are performed aiming to manage these damages. Among them, is the use of vegetal extracts. In this sense, the aim of this study was to evaluate the potential of black angico extract (Anadenanthera macrocarpa) in the management of P. brachyurus in cotton crop. The experiment was conducted in a greenhouse at the Phytopathology Laboratory of the Federal University of Piauí in Bom Jesus-PI. The experimental design was completely randomized, in a factorial scheme (2×6), composed of two sources of extracts (leaf and bark) of black angico under six concentrations (0, 20, 40, 60, 80 and 100 g L-1), with five replications per treatment. The plants were inoculated with 1900 specimen/juveniles and eggs, 96 h after the transplanting. Sixty days after the application of extracts, some agronomic variables of the cotton and P. brachyurus were evaluated. The volume and fresh root mass showed considerable gains for all concentrations with the leaf extract. The plant height was negatively influenced by concentrations above 60.83 g L-1 for both extracts. Regarding the parasitism, all the extract concentrations, regardless of the source (leaf or bark), showed suppressiveness to P. brachyurus. Therefore, the aqueous extracts of black angico present nematicidal action and favor the development of cotton plants.

Nematicidal Activity of Phytochemicals against the Root-Lesion Nematode Pratylenchus penetrans

“…The nematicidal activity of each phytochemical and the commercial nematicide oxamyl was assessed by direct-contact bioassays [ 15 , 16 ]. Briefly, 1 μL of phytochemical stock solution was added to 99 μL of a mixed-stage nematode suspension (for a final concentration of 2 mg/mL) per well in a 96-well microtiter plate (Carl Roth GmbH & Co. KG, Karlsruhe, Germany).…”

“…Also, marigold (Tagetes patula) is well-known for reducing P. penetrans populations in field experiments, its effect being persistent when employed as part of crop rotation [14,15]. Plant extracts employed as soil amendments have also shown suppressiveness towards other Pratylenchids [16,17].…”