Weed Research (2007) 47, 415-424

I. Riethmuller-Haage, L. Bastiaans, C. Kempenaar, V. Smutny and M.J. Kropff (2007)
Are pre-spraying growing conditions a major determinant of herbicide efficacy?
Weed Research 47 (5), 415-424
Abstract: To evaluate the effect of pre-spraying growing conditions on herbicide efficacy, two years of experimentation were conducted in which Persicaria maculosa plants were exposed to different light intensities for 1-4 days before metribuzin treatment. Specific leaf area, rather than plant growth rate or plant size, was the only parameter that correlated well with herbicide efficacy in both years of experimentation. The negative relationship between the ED₅₀ and the specific leaf area indicates that leaf characteristics might be an important determinant of herbicide efficacy, for instance through an effect on herbicide uptake. In the third year of experimentation this hypothesis was further investigated by raising six cohorts of weed plants at a 1-week interval and thus exposing them to a range of weather conditions. Clear relationships between uptake and herbicide efficacy were found for a combination of four plant species (Solanum nigrum, Senecio vulgaris, Chenopodium album and Brassica napus) and two herbicides (phenmedipham and bentazone). For phenmedipham, uptake was negatively correlated with global radiation and positively correlated with relative humidity. For the herbicide bentazone the opposite was found. These results were not species-specific. This study shows the importance of the sensitivity of herbicide × species combinations and indicates that pre-spraying weather information is relevant for the development of reduced dose rate recommendations.
(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): Corné Kempenaar

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Chenopodium album (weed)
	Polygonum persicaria (weed)
	Senecio vulgaris (weed)
	Solanum nigrum (weed)