Influences of nitrogen inputs on nematode populations under highbush blueberry

This study examined the effects of nitrogen fertilization on populations of Rotylenchus robustus, Pratylenchus crenatus, and Paratrichodorus renifer, and indices of free-living nematode community structure, in relation to highbush blueberry production in British Columbia, Canada. The field experiment was established in fall of 2008 with six replicate plots of each of four experimental N fertilization treatments: 0, 100, 150, and 200% of the annual application rate recommended for conventional blueberry production in the region. Nematode populations were quantified annually from 2009 through 2015, and then nematode populations and root biomass were quantified at seven sample dates from 2016 through 2019. Population densities of R. robustus were consistently greater in the 100% treatment than in the 0, 150, and 200% treatments which did not differ from each other. Population densities of P. crenatus were consistently greater in the 150% treatment than in the 0, 100%, and 200% treatments. The nematode structure index and two indices of diversity declined monotonically with N fertilizer rate, indicating broader changes in the soil food web that could have had indirect, feedback effects on population dynamics of the plant-parasitic nematodes.