Population dynamics of plant parasitic nematodes on pineapple (Ananas comosus ‘MD-2’) during the growth of the plant crop

In two commercial pineapple (Ananas comosus ‘MD-2’) farms, after six planting cycles, the population of nematodes during the plant crop was determined. Seven and eight samplings were carried out in the same terraces and beds, every 60 days after planting (Siquirres county farm at 60, 120, 180, 240, flower induction at 258 days, 60 and 120-days post flower induction, and Pital county farm at 60, 120, 180, 240, 300, flower induction at 360 days, 60 and 120 days, post flower induction). In both farms, 10 terraces that were planted with slips weighing 400 to 450 g and of the same planting age were selected for sampling. In each terrace and sampling time, the select guide leaves were marked on beds 2, 4, 6, 8 and 10 with colored spray paint. In each sampling, the plants neighboring the marked one, was extracted with a shovel and the roots present on the 5 plants were collected, placed in a marked plastic bag, and sent to the CORBANA Nematology laboratory for the nematode extraction. Root mass increased (P<0.0001) up to 180 days after planting, with a slight decrease until 120 days after flower induction (forcing) at the Siquirres county farm. At the Pital county farm, lower root mass was observed recording three peaks, one at 120 days after planting with 21.6 g, another at 300 days after planting with 33.5 g, and the last one 60 days after forcing with 25.5 g plant^-1 with differences (P<0.0001) among sampling times. In both farms, the predominant nematode was Pratylenchus spp. accounting for 99.0 and 96.4% of the phytoparasitic nematode community. The population of Pratylenchus increased as the vegetative cycle of the crop advanced up to 60 days post-forcing at the Siquirres farm and up to plant forcing at the Pital farm with differences (P<0.0001) among evaluations in both farms. According to the nematode thresholds established for the crop, the populations found warrant control measures to prevent losses in production.