Goosegrass is a weedy C4 species throughout the world and a major pest in turfgrass systems. Further research is needed to characterize morphological events of goosegrass germinating in late summer to enhance long-term management programs. The objective of this study was to determine whether goosegrass germinating on August 15 will complete a life cycle before the first killing frost, typically November 15 in Clemson, SC. A biotype from Clemson, SC, was collected and a growth-chamber experiment was conducted to simulate autumn maximum and minimum temperatures. Culm, leaf, root, and raceme biomass measurements were recorded weekly, and growth curves were modeled. The inflection point (i.e., point of maximum growth) occurred for the following growth parameters: culm dry weight at 26.5 d after emergence (DAE), leaf dry weight at 26.6 DAE, number of racemes per plant at 50.7 DAE, raceme dry weight (including germinable seed) at 56.0 DAE, and root dry weight at 42.1 DAE. The completion of the life cycle occurred on October 22 (68 DAE), approximately 3 wk before the typical first killing frost in Clemson, SC. In summary, turf managers need to address goosegrass that germinates through approximately the first week of September at this location to avoid production of viable seed.

Kyllinga species are becoming more prevalent in turfgrass sites throughout North America. The effects of nitrate (50, 200, and 400 mg L−1), temperature (33/24, 25/17, 19/11 C day/night, respectively), and light on seed germination of three Kyllinga species were investigated in growth chambers. Nitrate concentrations did not stimulate Kyllinga species seed germination compared with untreated seeds. All Kyllinga species seeds failed to germinate in darkness but resumed germination once they were placed in light. This is an important pest management strategy because a dense, uniform turfgrass stand with its minimum light penetration to the soil would minimize Kyllinga species seed germination. Higher temperatures increased seed germination rate and percentage of each species after 8 wk. Maximal (> 90%) K. brevifolia germination occurred 2 to 4 wk after initiation in every seed study, whereas K. squamulata seeds germinated continuously. Minimal (< 10%) K. pumila seeds germinated until alternating diurnal temperatures were imposed.