| The burrowing nematode, Radopholus similis, is the most important pest attacking bananas. Spread of burrowing nematodes is believed to be fairly recent, and is related to the distribution of infected planting material.; Monoxenic cultures of 13 burrowing nematode populations extracted from banana roots from Belize, Guatemala, Honduras, and Costa Rica, or from cultures obtained from Florida, Puerto Rico, Dominican Republic and Ivory Coast, were established on carrot discs. Aggressiveness and damage potential of these populations were evaluated by inoculating banana plants (Musa AAA, cv. Grande Naine). Burrowing-nematode populations varied in aggressiveness; their reproductive fitness was generally related to associated damage in the field. Necrosis of primary roots was closely related to reproductive fitness of the nematode populations. All populations had a low reproductive fitness in the resistant host, Pisang Jari Buaya, except a population from Ivory Coast which reproduced fairly well. This is the first report of a burrowing-nematode population parasitizing this important source of resistance to R. similis.; The molecular variability of the 13 burrowing-nematode populations was characterized using Random Amplified Polymorphic DNA. A high degree of genetic similarity was found among most Central American and Caribbean populations. Dissemination of this nematode with banana-planting material is probably responsible for the highly conserve genome. No relationship was found among the molecular similarity and the pathogenicity to citrus or reproductive fitness on bananas.; A standardized method for screening for resistance to burrowing nematodes under greenhouse conditions is proposed. Seven banana genotypes, ranging from susceptible to resistant, were used as indicator plants. Burrowing nematodes reproduced well in the susceptible cultivars False Horn, Grande Naine, Valery and Lacatan, but poorly in the resistant Pisang Jari Buaya and Yangambi. An intermediate reaction was observed with Pisang mas. The same trend was observed under field conditions, which is evidence that the proposed method is accurate and reliable.; Resistance of hybrids FHIA-01, FHIA-02, FHIA-03, and FHIA-21, to the burrowing nematode was assessed under greenhouse conditions. Nematode population numbers and root-necrosis indices did not differ among FHIA-01, FHIA-03 and the susceptible control, Grande Naine. |
