Poa annua: An annual species?

Abstract

As the Latin name annua implies, the species Poa annua L. is thought to have an annual life cycle. Yet, there are many reports in literature of P. annua persisting as a perennial. Considering that P. annua senescence patterns do not align with other true annual species, we hypothesized that P. annua is similar to other perennial, C3 turfgrass species that are subject to a confluence of environmental factors that can cause mortality. Four experiments were conducted in Knoxville, TN with the objective of determining environmental factors lethal to P. annua. A field monitoring study assessed 100 P. annua plants across ten grassland micro-environments from May to October 2020. Forty plants survived the summer and confirmed the existence of perennial P. annua ecotypes. Analysis of environmental factors at the time of plant death indicated soil moisture, soil temperature, and pathogenic infection were associated with mortality. A series of glasshouse or field experiments were conducted to investigate the effects of each factor on P. annua mortality. Soil moisture and soil temperature were not lethal to P. annua in the glasshouse, except under extreme conditions not typical in the field. A field study assessed mortality of plants from pathogenic infection and indicated that P. annua plants treated with fungicide throughout the summer survived year-round, whereas plants not receiving fungicide applications senesced. These findings support our hypothesis that P. annua is of a perennial life cycle, which can be influenced by environmental conditions. We suggest that the name P. annua is likely a misnomer based on its modern interpretation.

Turfgrass Use on US Golf Courses

“…The extensive reliance on herbicides for annual bluegrass control has resulted in high levels of herbicide resistance in certain plant populations and the belief that effective chemical control measures no longer exist (Heap 2023). In addition, although the Latin name annua implies that the species is an annual, recent research supports the hypothesis that Poa annua (annual bluegrass) is of a perennial life cycle and can be influenced by environmental conditions (Carroll et al 2022). Consequently, annual bluegrass prevalence on US golf courses is not likely to change in the foreseeable future.…”

“…Brosnan et al (2022) reported that the distribution of warm-and cool-season turfgrass species on putting greens across the United States differed from historical maps of growing zones, and suggested that the shift could be associated with a changing climate. Brosnan et al (2022) found that nearly 87% of survey respondents indicated that winter protective covers were used to maintain bermudagrass putting greens, including 100% of respondents in the US Transition region states of Kentucky, North Carolina, Tennessee, and Virginia. These protective covers are typically used when low-temperature injury is expected (DeBoer et al 2019).…”

A survey of ethofumesate resistant annual bluegrass (Poa annua) on US golf courses

“…Also, higher nitrogen application rates can increase annual bluegrass in turfgrass swards (Dest & Guillard, 1987; Skogley, 1975). Annual bluegrass encroachment is often positively affected by frequent irrigation (Cain et al., 2021) and frequent fungicide applications (Carroll et al., 2022). Additionally, annual bluegrass resumes active growth earlier in the spring than other desirable turf species, providing a competitive advantage (Vargas & Turgeon, 2004).…”

A bioassay to determine Poa annua responses to indaziflam

“…P. annua can be found on all seven continents globally (Chwedorzewska, 2008) and is referred to by various common names, including: annual meadowgrass, annual bluegrass, wintergrass, junegrass, suffolkgrass, speargrass, and walkgrass (Gibeault, 1971). Morphological diversity among P. annua is wide-ranging and its characterization as an annual species has been questioned, given that it does not exhibit monocarpic senescence (Carroll et al, 2021a;Carroll et al, 2022).…”