Carmem Dolores Gonzaga Santos

Espécies de Meloidogyne associadas a vegetais em microrregiões do estado do Ceará

O nematoide das galhas, genero Meloidogyne, e considerado o mais importante dentre os fitonematoides em razao das elevadas perdas provocadas em areas de exploracao agricola em todo o mundo. Identificar as especies de Meloidogyne presentes numa regiao e uma informacao primordial para o conhecimento da diversidade e dispersao populacional, alem de possibilitar adocoes de medidas efetivas de controle. Informacoes atualizadas sobre as especies de Meloidogyne que ocorrem em plantas em regioes produtoras do estado do Ceara, sao ainda escassas. O objetivo deste trabalho foi identificar as especies de Meloidogyne associadas a vegetais e a sua predominância nessas areas de plantio. A identificacao a nivel de especie foi realizada com base nos fenotipos da enzima esterase e a determinacao de racas pela reacao em plantas diferenciadoras. Setenta e quatro amostras de raizes infestadas com o nematoide, pertencentes a 42 especies vegetais, foram coletadas em areas produtoras de 19 municipios do Ceara pertencentes a dez microrregioes. Das 74 populacoes obtidas, 27 apresentaram fenotipos tipicos de M. incognita (I1 e I2), 20 de M. enterolobii (M2), 15 de M. javanica (J3), cinco de M. arenaria (A2) e uma de M. hapla (H1). Em seis populacoes, contudo, os fenotipos de esterase observados diferiram dos padroes de Meloidogyne conhecidos no Brasil, sendo entao referidos como Meloidogyne sp. Dentre as 68 associacoes entre plantas e especies de Meloidogyne bioquimicamente identificadas, 25 sao relatadas pela primeira vez no Ceara. Esse trabalho possibilitou atualizar informacoes relativas a ocorrencia, distribuicao e novos relatos do nematoide das galhas em areas agricolas do estado do Ceara.

DISPERSÃO DE Meloidogyne enterolobii EM POMARES DE GOIABEIRAS EM MUNICÍPIOS DO ESTADO DO CEARÁ

Among the factors negatively impacting guava (Psidium guajava) crop in Brazil, one of the most important is the root-knot nematode, Meloidogyne enterolobii, which may cause considerable yield losses and even the cessation of guava cultivation in some areas. In addition to affecting guava, the pathogen has been reported as a parasite in various other crops, among them both oleraceous and ornamental crops, as well as in spontaneous vegetation. The aim of this study was to verify the occurrence of M. enterolobii in plants collected in guava orchards in different counties of Ceará state, identified through electrophoresis with the isoenzyme esterase, and to observe its infecting behavior into Meloidogyne differentiating plants. Fifty root samples from guava, tasselflower (Emilia fosbergii), and jurubeba (Solanum paniculatum), were collected in 13 counties from eight micro-regions in the state of Ceará. In all analyzed samples, only esterase phenotype M2 (Rm: 0.6; 0.9), characteristic of M. enterolobii, was detected, showing that the nematode is widespread in orchards throughout the state, where is affecting these fruit tree, and that it is also able to parasitizing plants of the spontaneous vegetation. Based on the results, this nematode currently constitutes a serious threat to guava plantations in Ceará, and effective control mechanisms are crucial to prevent the spread of this pathogen to other, still unaffected, areas.

Ação de extratos de plantas medicinais sobre juvenis de Meloidogyne incognita raça 2

Phytonematodes are parasites that seriously affect crops worldwide, compromising agricultural production and sometimes preventing the use of many cultivated areas. The search for alternative control measures to replace conventional nematicides is a global concern, and explains research into natural substances due to their being efficient and environmentally friendly. The aim of this study was to evaluate the effect of plant extracts from the false daisy (Eclipta alba), basil (Ocimum basilicum), mugwort (Artemisia vulgaris), citronella (Cymbopogon winteranus), water willow (Justicia pectoralis), comfrey (Symphytum officinalle), cuban mint (Mentha x vilosa), pink root (Spigelia anthelmia), epazote (Chenopodium ambrosioides) and wild mint (Mentha arvensis) on motility and mortality in juveniles of Meloidogyne incognita race 2. Extracts, obtained from dried leaves under infusion or macerated in water, were diluted and spread onto Petri dishes to which were added 50 second-stage juveniles (J2). After remaining for 48 hours in the extracts, all the J2, both mobile and immobile, were counted and then transferred to water, where after 24 hours, the percentage of dead J2 was determined. Any still active J2 were inoculated into ‘Santa Clara’ tomato seedlings in a greenhouse so as to evaluate their infectivity. The macerated extracts of the medicinal plants, except for the citronella, cuban mint and wild mint, showed high nematicide activity, with over 70% of the J2 dead. Total mortality was seen with the extracts of pink root, false daisy and epazote. The absence of galls in the root system of the inoculated tomato plants confirmed the toxic effect of these extracts.

Controle alternativo de nematoide das galhas (Meloidogyne incognita) raça 2, com óleos essenciais em solo

The action of natural products on plant pathogens has been investigated with the aim of evaluating their effectiveness in the alternative control of diseases, especially in organic agriculture. The aim of the present study was to evaluate the effect of essential oils of rosemary pepper (Lippia sidoides) and citronella grass (Cymbopogon winterianus) on the control of M. Incognita race 2, in tomato (Solanum lycopersicum) and celosia (Celosia plicata). Thus, an assay was conducted in 6 x 2 factorial arrangement, with five replicates. It was carried out in a greenhouse of the Plant Health Sector of the Department of Phytotechny/CCA/UFC, in the period from April to June 2007. The seedlings used in this test were transplanted into plastic pots containing 2 kg of sterile soil, in which, at 24 hours after transplanting, 4,000 eggs/J2 of M. incognita, race 2, were inoculated, except for negative controls. For 50% of the number of pots, 100 ml of the solutions of each essential oil were soon applied to each pot at the concentration of 2.5 ml L-1. After 48 hours, the same amount was applied to the remaining pots. This volume corresponds to 60% of the field capacity of this substrate, which was previously calculated. The final evaluation was at 45 days after inoculation. The following variables were analyzed in relation to the nematode: number of galls (NG), number of eggs (NE), egg mass index (EMI), reproduction factor (RF), reproduction factor reduction (RFR). Regarding the development of plants, the measured parameters were: plant height, shoot fresh and dry weight, and fresh weight of the root system. The nematode reproduction revealed to be less efficient in tomato. The employed essential oils reduced the reproductive rate of the nematode by 83 and 29% in tomato and celosia, respectively. The times of application of essential oils differed as to the nematode reproduction for the number of galls and the reproduction factor.