ABSTRACT The objective of this work was to quantify damage and yield losses in lettuce parasitized by Meloidogyne javanica, as well as the growth characteristics of naturally cultivated field plants infested by this pathogen. The experimental area consisted of four seedbeds of 10.0x1.60 m cultivated with 160 plants in each, totaling 640 plants. The damages and yield loss were quantified in four evaluations (Ev1, Ev2, Ev3, and Ev4), with each evaluation corresponding to a cultivation cycle. The four plantings were made in the consecutive form. The fresh mass weight and dry mass weight (FMW and DMW, respectively), gall number (GN), and final population of the nematodes (FP) were evaluated. The population increase of M. javanica caused a reduction in the FMW and DMW in all evaluations. In Ev1 and Ev2, 100% of the plants were commercialized. In Ev3 and Ev4, 7% and 65% of the plants, respectively, could not be commercialized. The Ev4 was completely unviable since the produce had losses of U$ 7.42; U$ 23.19 and U$ 1,484.10 for the cultivation of 640; 2,000 and 128,000 plants, respectively. The economic threshold in Ev4 was 10,151 nematodes/plant or 109 galls/plant.

RESUMEN El objetivo de este trabajo fue cuantificar el daño agronómico en un cultivo de lechugas parasitadas por Meloidogyne javanica y caracterizar el crecimiento de plantas cultivadas en un campo infestado por este patógeno. El estudio se hizo en cuatro camas de 10.0 x 1.60 m cultivadas con 160 plantas en cada una, totalizando 640 plantas por cada ciclo de cultivo. Se hicieron cuatro tratamientos (Ev1, Ev2, Ev3 y Ev4), correspondientes a un ciclo de cultivo. Las cuatro plantaciones se realizaron de forma consecutiva y se seleccionaron 100 plantas al azar para cuantificar el efecto del nematodo en las lechugas. Los parámetros evaluados fueron peso fresco (PMF), peso seco (PMS), número de agallas (NG) y la población final de nematodos (PF). El aumento de la población de M. javanica provocó una reducción de PMF y PMS en todas las evaluaciones. En Ev1 y Ev2 se vendió el 100% de las plantas. En Ev3 y Ev4 hubo un 7% y un 65% de las plantas, respectivamente, que no pudieron venderse. El cuarto ciclo de cultivo (Ev4) resultó completamente inviable, ya que las pérdidas fueron de U $ 7,42; U $ 23,19 y U $ 1.484,10 para el cultivo de 640, 2.000 y 128.000 plantas, respectivamente. El umbral económico en Ev4 fue de 10.151 nematodos /planta o 109 agallas /planta.

RESUMO: O nematoide-das-galhas é um dos mais importantes problemas fitossanitários para o cafeeiro conilon, por reduzir a produtividade e ser de difícil manejo. Objetivou-se estudar a infectividade e os danos causados por M. incognita raça 1 na variedade de café conilon de maturação intermediária “Jequitibá Incaper 8122”. O experimento foi conduzido em casa de vegetação, em DIC, com cinco repetições. Os clones que compõem a variedade “Jequitibá Incaper 8122” foram inoculados com 2.000 ovos + juvenis de segundo estádio de M. incognita raça 1. Plantas não inoculadas constituíram a testemunha. As avaliações foram realizadas 180 dias após a inoculação, sendo avaliados: altura da planta (ALT), diâmetro do caule (DCA), número de folhas (NFO), área foliar (AFO), número de ramos plagiotrópicos (NRP), número de nós (NN), teor de clorofila (CLO), massa seca da parte aérea (MSA), matéria fresca da raiz (MFR), população final (PFN) e fator de reprodução (FRE). O nematoide reduziu o NFO nos clones 208 e 209, NRP nos clones 201, 203, 207 e 208, NN nos clones 203, 207, 208 e 209, CLO nos clones 201, 204, 206, 207 e 209, MSA nos clones 201, 203, 204 e 205 e MFR nos clones 205 e 207. PFN e FRE de M. incognita raça 1 foram maiores nos clones 208, 201, 207 e 203; o clone 202 teve a PFN e a FRE igual a zero, apresentando-se imune ao nematoide. O clone 206 apresentou o menor valor de FRE entre os clones parasitados por M. incognita.

ABSTRACT: Root-knot nematode is one of the most important phytosanitary problems for Conilon coffee, as it reduces productivity and is difficult to handle. We aimed at studying the infectivity and damage caused by M. incognita race 1 in the “Jequitibá Incaper 8122” intermediate maturity coffee variety. The experiment was conducted in a greenhouse, in completely randomized design, with five replicates. The clones composing the variety “Jequitibá Incaper 8122” were inoculated with 2,000 eggs + second-stage juveniles of M. incognita race 1. Uninoculated plants were the control. Evaluations were performed 180 days after inoculation, considering the plant height (H), stem diameter (SD), number of leaves (NOL), leaf area (LA), number of plagiotropic branches (NPB), number of nodes (NN), chlorophyll content (CHLO), shoot dry matter (SDM), root fresh matter (RFM), final population (FNP), and reproduction factor (NRF). The nematode reduced NOL in clones 208 and 209, NRF in clones 201, 203, 207 and 208, NN in clones 203, 207, 208 and 209, CHLO in clones 201, 204, 206, 207 and 209, SDM in clones 201, 203, 204 and 205 and RFM in clones 205 and 207. M. incognita race 1 FNP and NRF were larger in clones 208, 201, 207 and 203. Clone 202 had FNP and NRF equal to zero, being immune to the nematode. Clone 206 presented the lowest NRF value among clones parasitized by M. incognita.