| The cosmopolitan lance nematode (Hoplolaimus galeatus (Cobb) Thorne) feeds on the roots of numerous plant species, and includes turfgrasses. I evaluated the reproductive potential of the lance nematode across four cool- (C3) and four warm-season (C4) turfgrasses in the greenhouse given a sandy rootzone and two soil temperatures of 20 and 30 C. Lance nematode reproductive fitness was better in C3 than C4 turfgrasses, and was similar across soil temperatures. In a second series of greenhouse experiments H. galeatus reproductive potential was similar among 20 and 30C soil temperatures, and across A-4, Crenshaw, L-93 and, Penncross creeping bentgrass cultivars. Lance nematodes reduced root biomass and root length but had no aboveground effects, whereas warm soil temperature reduced both above- and below-ground plant health measurements.; In the field, dense H. galeatus populations were aggregated spatially, and were capable of seasonal fluctuations. H. galeatus densities increased from June to August, declined by 50% by September, and then increased to fall. The midsummer drop of lance nematode population densities mirrored the midsummer physiological decline of creeping bentgrass putting greens common in Kansas. Summer cultural practices could influence lance nematode populations. Lowering the clipping height from 4.0 to 3.0 mm generally reduced lance nematode populations, but varied according to cultivar. Irrigation frequency and creeping bentgrass cultivar did not influence H. galeatus populations. The population structure of H. galeatus was strongly associated with bentgrass root feeding habit, and a majority of juveniles were endoparasitic, while a majority of adults were endoparasitic. Additionally, pulses of endoparasitic juveniles were abnormal, and were associated with midsummer creeping bentgrass decline and stressful putting green cultural practices, such as over- or under-irrigation.; I compared visual ratings of turfgrass quality and cover with narrow band multispectral radiometry (MSR), and found a trained rater could effectively and efficiently record lance nematode damage.; In the field, I found that cultural practices influenced the negative effect that lance nematodes can have to creeping bentgrass putting greens. Further using field microplots, we propose the current damage threshold of lance nematodes to creeping bentgrass be increased from 400 to 700 H. galeatus per 100 g soil. |
