Defra - Department for Environment, Food and Rural Affairs.

Science Search

Science and Research Projects

Return to Science Search homepage   Return to Project List

To determine the effect of strategies of herbicide use on sensitivity of weed populations - HH3401SFV

The minimisation of pesticide use forms part of the DEFRA policy objectives of encouraging sustainable, competitive and safe food production whilst enhancing biodiversity. It has been shown that populations of a number of farmland birds, invertebrates and plants have declined in recent years. Changes in agriculture, including herbicide use, are implicated in this decline. This is because herbicides may have both direct effects and indirect effects on field biodiversity through subtle changes in the plant community composition. These changes are often difficult to detect in the short-term and may be delayed by the buffering capacity of the weed seedbank. For example, changes may occur in weed germination, early growth, competitive ability that result in subsequent shifts in species dominance over time. However, until effective alternatives have been developed, chemical weed control will remain essential for vegetable growers. One approach to limiting herbicide inputs has been to apply single or sequential sprays of reduced doses of herbicide, however, this strategy also raises a number of key issues for growers that form the main objectives of this project

1. What would be the characteristics of the kind of weed flora likely to develop from a reduced rate strategy and does this weed flora carry any added benefit?
2. Are growers likely to encounter undesirable new weed problems, such as tolerance, as a result of adopting a reduced rate regime and are there strategies that can be suggested to minimise this?
3. Will a reduced herbicide regime affect crop yields over a number of years and be cost effective?

HRI has access to a unique long-term reduced herbicide trial with accompanying baseline data at HRI Kirton, which is now entering its 7th season. Observations made from this unique long-term field study will be underpinned by measurements made in the glasshouse. The glasshouse studies will focus on changes in response to reduced herbicide rates both in terms of the potential susceptibility and ecological behaviour of survivors and progeny. The results will allow the development of generic advice to maintain the sustainability of a reduced rate herbicide strategy. This will be combined with an economic analysis of a reduced rate strategy using a scenario testing demonstration trial at HRI-Wellesbourne including crops.

The intended outputs from the project will be a grower leaflet that gives the findings of the 9-year study and also advice on the issues raised above. Refereed papers will also be submitted to appropriate scientific journals.
Objective 1:
01/04/02 to 30/09/05
To formally quantify whether there have been shifts in the biodiversity of the natural background vegetation that can be attributed to the different herbicide/application rate regimes.
Objective 2:
01/04/02 to 30/09/05
To determine whether progeny from weeds surviving different herbicide rates show any for potential development of herbicide resistance measurable change in competitive ability or fecundity as a result.
Objective 3:
01/04/02 to 30/09/05
To demonstrate the economic costs and benefits of repeated applications of reduced herbicide rates in field vegetable production
Time-Scale and Cost
From: 2002

To: 2005

Cost: £455,239
Contractor / Funded Organisations
Warwick - HRI, Horticulture Research International
Natural Resource Use              
Pesticide use              
Sustainable Farming and Food              
Sustainable Production              
Weed Control              
Fields of Study