Nematode distribution in roots of banana (Musa AAA cv. Valery) in relationto plant height, distance from the pseudostem and soil depth

The horizontal and vertical distribution of plant plant parasitic root nema todes on banana (Musa AAA cv. Valery) was determined in a sandy clay loam i n Costa Rica. Root samples were taken from soil blocks at distances of 0 to 30, 30 to 60, and 60 to 90 cm from the pseudostem, from 0 to 120 cm depth at intervals of 15 cm, and from plants of 120, 150, 180 or 210 cm high (non -flowering), plus a set from plants at flower stalk. The horizontal distanc e from the pseudostem affected the percentage of Radopholus similis, Pratyl enchus spp., and total nematodes (R. similis + Helicotylenchus spp. + Meloi dogyne spp, + Pratylenchus spp.). There was a significant effect of soil de pth on the density of each genus. An Interaction between soil depth and pla nt height and with horizontal distance was found for R. similis and total n ematodes. For the three horizontal distances from the pseudostem, the perce ntage of each genus decreased with soil depth. Higher percentages of R. sim ilis and total nematodes were found at 0 to 30 cm horizontal distance from the pseudostem than at greater distances in the upper 30 cm of the soil pro file. Therefore, samples for monitoring nematode populations in bananas sho uld be taken within a horizontal distance of 0 to 30 cm from the plant base and down to 30 cm deep from the soil surface. Additional studies are neede d to relate the nematode population density at this sampling point to yield .