Reaction of weeds, found in vegetable production areas, to root-knot nematodes Meloidogyne incognita and M. enterolobii

Abstract

Root-knot nematodes cause great damage to vegetable crops in Brazil, besides having a large range of host plants, such as weeds. Weeds can maintain the inoculums or even favor the multiplication of these nematodes. In this study we evaluated the reaction of selected weed species, present in a vegetable production area, to root-knot nematodes Meloidogyne incognita and M. enterolobii. The trials were conducted in a greenhouse at Embrapa Hortaliças, Brasília-DF, in a completely randomized design with six replicates. Fifteen weed species were evaluated for M. incognita race 1, and 16 weed species were evaluated for M. enterolobii. Two tomato cultivars were evaluated as resistance and susceptibility standards. Gall index (IG), egg mass index (IMO), number of eggs per gram of roots (eggs/g roots) and reproduction factor (FR) were evaluated. M. enterolobii survives and multiplies more easily in weeds collected in vegetable production areas than M. incognita race 1 and, the great majority of weed species evaluated in this study are hosts of both nematode species. Only the species Urena lobata, Sonchus oleraceus, Euphorbia heterophylla, Melampodium perfoliatum and Tagetes sp. were immune to M. incognita race 1. All evaluated species are either hosts or favor the multiplication of M. enterolobii. The species which are the most susceptible to M. incognita race 1, and therefore require greater control of crops infected by this nematode are Ipomoea nil, I. triloba and Eleusine indica, and for M. enterolobii are I. nil, Solanum americanum, Hyptis suaveolens, Portulaca oleracea, I. triloba and Euphorbia heterophylla.

As a Transitional Host, Weed Solanum nigrum L. Increases the Population Base of Root-Knot Nematode Meloidogyne enterolobii for the Next Season

“…Alternanthera tenella, Acanthospermum australe, Tagetes sp., Sida cordifolia, Digitaria horizontalis, and Eleusine indica even are not hosts for M. enterolobii, although they can be infected by M. enterolobii. In the present study, M. enterolobii showed a high reproductive ability in S. nigrum L., with an RF of 48.04 ± 14.71, which was higher than that in related species, such as Solanum americanum [10], tomatoes [32], and chili pepper [33], although the time of root examination was brought forward to 35 DAI. In addition, M. enterolobii presented a fast development rate in S. nigrum L. The female juveniles of M. enterolobii only took 21 DAI to reach the adult stage, and at 25 DAI, they formed obvious egg masses on the roots of S. nigrum L., which was faster than that on tomato variety VFNT [34], Capsicum spp.…”

“…M. enterolobii has been reported to infect species of more than 29 families worldwide [25][26][27][28][29][30][31], including certain species of weeds [10][11][12][13][14][15]31]. However, not all species of weeds that could be infected are suitable hosts for M. enterolobii development and reproduction.…”

“…Some species of weeds were reported to be hosts of Meloidogyne arenaria, Meloidogyne incognita, and Meloidogyne javanica [7,8], and some species were reported to be infected by M. enterolobii, but only a few species of weeds, such as Ipomoea nil, Euphorbia heterophylla, and Solanum americanum, etc. were good hosts for M. enterolobii [9][10][11][12][13]. RKNs could rapidly reproduce in good hosts, which contributes to the rapid increase in nematode populations.…”

Caracterização do crescimento e produção de óleo essencial da erva baleeira (Varronia curassavica Jaqc)

“…Os nematoides das galhas são relatados como uma das principais pragas com potencial de provocar declínios de produtividade das diversas culturas em todo o mundo e são responsáveis por perdas anuais de aproximadamente U$ 157 bilhões (Pinheiro et al, 2019). O controle desses organismos deve ser planejado com a integração de vários métodos e apresentar baixo custo, sendo recomendados, com frequência, a rotação de culturas, o uso de genótipos resistentes, uso de indutores de resistência e os controles químico e biológico (Conduta et al, 2020;Lopes & Ferraz, 2016).…”

Nemátodos asociados a malezas en San Lorenzo, Paraguay

“…un papel importante en la ecología de los nemátodos, pues pueden mantener o elevar la densidad de población de estos en el suelo, principalmente entre cada ciclo productivo (Pereira-Braz et al 2016;Ntidi et al 2012;Bellé et al 2017). Además de dificultar la implementación de medidas de manejo agronómicas eficientes, las malezas hospederas de nemátodos poseen otro aspecto problemático, pues en regiones tropicales y subtropicales, como el caso de Paraguay, tienen un vigoroso desarrollo durante todo el año, generando de forma continua nuevos individuos con grandes capacidades de albergar nemátodos (Pinheiro et al 2019;Gharabadiyan et al 2012). Previas investigaciones han demostrado la asociación de nemátodos y malezas, y en lo referente a América del Sur, Ferraz et al (1978) abordaron por primera vez la perspectiva de la ecología de ciertas especies de nemátodos en asociación con malezas en Brasil, constatando que géneros de Helicotylenchus, Pratylenchus, Rotylenchulus, Xiphinema, Tylenchus, Trichodorus y Hemicycliophora se asociaron a diversas especies de malezas instaladas en parcelas con hortalizas.…”