Southern sting nematode (Ibipora lolii): its occurrence and population dynamics in Western Australia and an assessment of resistance and tolerance to the nematode in turf grasses

Abstract

Despite being recognised as a serious pest of turf grasses in Australia, there has been limited research into the southern sting nematode (Ibipora lolii). This study examined its occurrence and population dynamics in the Perth region of Western Australia and assessed the level of resistance and tolerance of turf grasses to this nematode. In a systematic survey of 90 municipal sports fields on which kikuyu was the most common turf species, I. lolii was detected in 51% of sites. The mean population density was 27 nematodes/200 mL soil, but was almost eight times higher in localised areas where symptoms were severe. Infested turf tended to be relatively sparse and have a shallow root system. In a 2-year population dynamics study on a kikuyu sports field, I. lolii reproduced year-round, but exhibited a seasonal pattern of fluctuation in population density. Numbers increased when conditions were cool and wet during the winter rainfall period, peaking in October, and then declined during the hot and dry irrigation season. Although the population density of I. lolii was always greatest in the upper 10 cm of the soil profile, nematodes were consistently recovered from depths of 50–70 cm, showing that it was capable of deep vertical movement. A field experiment comparing four cultivars of couch and two cultivars of kikuyu showed that none of the cultivars exhibited resistance or tolerance to I. lolii. Nematode numbers increased rapidly in infested plots, regardless of cultivar, while in comparison with non-infested plots, the mean total plant biomass and root dry weight were reduced by 53% and 88%, respectively.