Weed Populations For Population Comparisons and 'Baseline Studies'

There is an increasing awareness that different populations of the same plant species may react differently to environmental factors and chemical treatments. This may be as extreme as two populations of Galium aparine, one of which predominantly germinates in autumn and winter, the other in spring. Similarly there is clearly evident morphological variation between the dozens of populations of Echinochloa crus-galli growing in different countries (see Echinochloa in the main weed list or read a leaflet with more discussion). 

 

Herbicide-resistant biotypes are an example of the development within a species of physiologically differentiated populations. More subtle differences may occur between geographically separated populations of a weed species, which although not obvious to a researcher with a local perspective, are ecologically (and agronomically) important over the range of the species. This less evident variation includes such characters as differential reactions to day length between populations of Xanthium strumarium from different latitudes and subtle differences in herbicide susceptibility between populations of a weed species within a relatively small geographical area, such as a single field.  

 

The need to test candidate herbicides on a range of populations of the same target species is under consideration by several registration bodies and other organisations. For instance HRAC is considering the establishment of ‘Baseline Studies’ to evaluate the variation in efficacy of new herbicides across a range of populations of the target species before that species becomes widely exposed to the herbicide. Documentation of the initial natural variability in response of different populations to the herbicide is expected to help evaluate possible future suspicions of changes in weed susceptibility (tolerance or resistance) caused by exposure of a population to the herbicide.  

 

Herbiseed has collected several populations of temperate arable weeds from across Europe to supply this need for weed population studies. Until the extent of demand is clear, only limited quantities of seed are available from a small number of species. Samples of each population are available at $ 60/£30/€50 per 25g. Please order these by e-mail as our online ordering system cannot handle multiple populations.  

 

For biotypes of Echinochloa, please go to the Echinochloa entry in our main list.

 

Return to weed populations table.