Back to our roots

Back to our roots: Investigating relationships of creeping bentgrass root biomass and Hoplolaimus galeatus populations

By Aaron Tucker Graduate Student, Virginia Tech

The goal of this work is to determine if the relationship of creeping bentgrass (CBG) root biomass and lance nematode populations can be used as an indicator of plant health. To understand these effects, a 4x5 factorial design was arranged with 4 levels of urea (46-00) nitrogen (0, 0.25, 0.5, and 1lb per M) and 5 levels of lance nematode populations (0, 100, 500, 1500, and 3000 nematodes) over 16 weeks. Two-inch plugs were removed from an L93 CBG putting green at the Virginia Tech Turfgrass Research Center (n=80), maintained at a mowing height of 0.125 inches, and levels lance were inoculated with an acclamation period of 18 weeks. Nitrogen applications and digital image analysis occurred bi-weekly and hyperspectral radiometry was measured daily to evaluate both visible and spectral indices. Destructive sampling occurred every 4 weeks where one representative of each factor combination was removed, nematodes extracted, verdure discarded and subjected to a muffle furnace to collect root biomass. Inoculation levels of 0, 100, and 1500 recovered different counts of lance nematodes, while counts of 500, 1500, and 3000 compared similarly. Data for root biomass and lance counts was not normally distributed and required a square root data transformation. A negative relationship of transformed root biomass by transformed lance counts was observed at 12 weeks while all other samplings showed no relationship. This suggests a moderate relationship showing lance counts can negatively impact root biomass. There were no effects of nitrogen on lance counts or root biomass. Additional work will aim to confirm the effects of nitrogen from urea and point turfgrass managers toward using root biomass along with nematode counts to properly address management of these plant parasitic nematodes.

Figure 1. Linear regression of root biomass in grams by lance nematode counts at 12 weeks. Nearly 40% of the change in root biomass can be explained by lance nematode counts. This data is negatively correlated and shows that as lance nematode counts increase, root biomass decreases.