Distribution of pest nematodes on sugarcane in south Queensland and relationship to soil texture, cultivar, crop age and region

Five plant-parasitic nematode species were found to be widespread on sugarc ane crops surveyed in south Queensland, namely Pratylenchus zeae, Meloidogy ne javanica, Paratrichodorus minor, Helicotylenchus dihystera and Tylenchor hynchus annulatus. Apart from Meloidogyne, high nematode populations were f ound in most soil types, suggesting more extensive crop losses could be occ urring than previously estimated. The most important pests were P. zeae and M. javanica, as they were often found at high densities and their pathogen icity on sugarcane is established. Mean densities for most nematode genera did not differ significantly betwee n sugarcane cultivars, except that fewer Pratylenchus were associated with cultivar CP51-21 than other cultivars surveyed. The density of Pratylenchus in roots was significantly higher in plant crops than in ratoon crops, whe reas the density of Paratrichodorus was highest in first and second ratoons .