Weed Research (1993) 33, 149-160

D.M. Anderson, C.J. Swanton, J.C. Hall and B.G. Mersey (1993)
The influence of soil moisture, simulated rainfall and time of application on the efficacy of glufosinate-ammonium
Weed Research 33 (2), 149-160
Abstract: Laboratory experiments were conducted to determine the effects of soil moisture, simulated rainfall and time of day of spray application on the efficacy of glufosinate-ammonium in barley (Hordeum vulgare L. cv. 'Samson') and green foxtail (Setaria viridis (L.) Beauv.) plants. Environmental variables examined were three soil moisture levels (18% moisture, 50% moisture and saturated), three intensities of simulated rainfall following spray application [drizzle (4 mm), moderate (9 mm) and heavy (22 mm)] and two times of spray application (begin ning and end of a 16-h photoperiod). The efficacy of 100 g ha⁻¹ glufosinate-ammonium on barley was greatest at 18% soil moisture when measured by both ammonia and dry weight accumulation in the shoots. At the same dose green foxtail showed less ammonia accumula tion at 18% soil moisture than under other soil moisture levels, but showed no significant differences in dry weight accumulation 14 days after treatment (DAT). Simulated rainfall shortly after spraying reduced the efficacy of glufosinate-ammonium on both species. At the field dose of 800 g ha⁻¹, a rain-free period of 1-8 h was necessary for barley, while a period of less than 20 min was necessary for green foxtail to obtain herbicidal activity comparable with that of treated plants which received no rain. Based on dry weight accumulation, barley plants were equally sensitive and green foxtail plants were significantly more susceptible when glufosinate-ammonium was applied at the end compared to the beginning of the photoperiod. Both species accumulated significantly more ammonia in the shoots during the initial 24 h following application if sprayed at the end of the photoperiod. Of the environmental factors examined in this study, rainfall after spray application caused the greatest reduction of glufosinate-ammonium efficacy.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Clarence J. Swanton

Research topic(s) for pests/diseases/weeds:
control - general
environment - cropping system/rotation

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Setaria viridis (weed)