Evaluation of four screening methods for resistance to Meloidogyne exigua in coffee seedlings

Four methods of infestation namely: a) sand infestation with small pieces of root-knots; b) irrigation of sand with nematode eggs and larvae; c) the combination of a and b, and d) soil infested plus sand, were compared to develop a screening method for the evaluation of resistance of coffee seedlings to Meloidogyne exigua. Seedlings of Mundo Novo cultivar belonging to the Coffea arabica species were obtained by sowing seeds in plastic trays containing sand. A five point scale was used to determine the intensity of the nematode attack with grades 1 and 5 indicating absence of the parasite and abundant gall formation, respectively. The infestation of sand with small pieces of diseased roots plus the irrigation of the trays with a suspension of nematode eggs and larvae during the development of the seedlings resulted in abundant gall formation 60 days after the first sand infestation. The evaluation made 150 days after the seed germination showed that methods a, b and c were effective in inducing a severe attack of the seedlings. The data obtained indicate clearly the possibility of screening coffee seedlings for resistance to M. exigua, by using sand infested through small pieces of root-knots and irrigation with nematode eggs and larvae.