Abstract

The study aimed to evaluate the control of Meloidogyne incognita in resistant and susceptible tomato genotypes treated with hydrogel containing avocado extracts (Persea americana Mill.). The methanolic extract of avocado seeds was evaporated and re-suspended in distilled water containing Tween 80 (0.6%). The extract was prepared with the following concentrations: 100, 200, 400, 800 and 1000 mg L^-1. The hatching, motility and mortality of juvenile were evaluated, in vitro, and from these results, we selected the most nematocide concentration which was incorporated into different hydrogel doses (0.1, 0.25, 0.5, 0.75 and 1.0 g pit^-1), for in vivo testing. The hydrogel containing avocado extract was added to the pits of tomato plants during transplanting, and after three days, M. incognita was inoculated. After 30 days, the relative chlorophyll content was assessed, along with the total volume of root, the number of galls and egg masses, viability of the egg mass, and number of eggs and juveniles per root system in 100 cm³ of soil. From these assessments, the most effective dose in the control of nematodes was tested again with the extract concentrations of 1000, 2000, 4000, 6000 and 8000 mg L^-1 in the hydrogel, which was added to the pits at the time of transplantation. After 30 days of inoculation the same evaluations were performed. In vitro, the concentration of 1000 mg L^-1 of the avocado extract was the most effective in reducing the hatched juveniles, while motility and mortality were not influenced. In vivo, 1.0 g pit^-1 dose in the first test had greater control of nematodes in susceptible plants for all variables assessed. It was incorporated into the pits of tomato plants for the realization of the second test. In this, the concentration of 8000 mg L^-1 was the most effective in controlling M. incognita. Therefore, the avocado seed extract served in hydrogel has the potential to control M. incognita in tomato plants.

Key words: Avocado tree, alternative control, plant extract, hydrogel, motility, mortality, galls nematode.