WeedTurf: a predictive model to aid control of annual summer weeds in turf

Abstract

Predicting weed emergence is useful for planning weed management programs. Unfortunately, our ability to anticipate initial emergence and subsequent levels of emergence from simple field observations or weather reports is often inadequate to achieve optimal control. Weed emergence models may provide predictive tools that help managers anticipate best management options and times and, thereby, improve weed control. In this study, the germination characteristics of four annual grass weeds (large crabgrass, goosegrass, green foxtail, and yellow foxtail) were investigated under different temperatures and water stresses to calculate base temperatures and base water potentials. These parameters were used to develop a mathematical model describing seedling emergence processes in terms of hydrothermal time. Hydrothermal time describes seed germination in a single equation by considering the interaction of soil water potential and soil temperature. The model, called WeedTurf, predicted emergence with some accuracy, especially for large crabgrass (lowest efficiency index [EF] value 0.95) and green foxtail (lowest EF value 0.91). These results suggest the possibility of developing interactive computer software to determine the critical timing of weed removal and provide improved recommendations for herbicide application timing.

Connecting differential responses of native and invasive riparian plants to climate change and environmental alteration

“…We selected soil temperature as the best overall integrator of thermal regimes at our sites due to (1) rapid and frequent switching between flooded and drained conditions, (2) rapidly changing water depths, (3) differences in mean depths between sites, and (4) the role of soil temperature as a regulator of spring emergence of noxious plant species (Masin et al 2005). Use of water temperatures might mean that at any given time we would be comparing air temperatures at a drained location to water temperatures at an inundated site.…”

Seed bank modelling of volunteer oil seed rape: from seeds fate in the soil to seedling emergence

“…The mathematical models based on characterising the variation that occurs in germination times among individual seeds in a population can describe and quantify the effects of temperature and water potential on weed seed germination (Bradford, 2002). There are many reports using HTT models to predict weed seed germination or emergence (Kebreab & Murdoch, 2000;Masin, et al, 2005;Bair et al, 2006;Martinson et al, 2007;Schutte et al, 2008), but there was no information available on HTT parameters for volunteer oilseed rape seed germination.…”

Modelling Soil Water Retention for Weed Seed Germination Sensitivity to Water Potential

“…The VG 4 model has one less parameter making it more parsimonious than the VG 5 model. The VG 4 model may also provide a superior estimation of the water retention relationships compared to the VG 5 model due to independence of the n and m parameters in the VG 5 model, that can lead to Blackgrass Alopecurus myosuroides Huds. [51] distinctiveness problems in the estimation process, resulting in a less accurate description of the SWRC in the dry range [52].…”

“…At the minimum threshold (base) water potential, seeds do not imbibe sufficient water to initiate embryo growth and complete the germination process. The minimum threshold water potential at which germination ceases to occur in many agricultural weeds ranges from −0.1 to −1.5 MPa [5,6]. Accurate representation of the SWRC over a wide range of water potential minimum thresholds is required for predictive modelling of seed germination.…”