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To determine the effect of strategies of herbicide use on the sensitivity of weed populations in field vegetable crops - HH2010SFV

Description
The minimisation of pesticide use forms part of the MAFF policy objectives of encouraging environmentally-friendly farming. In addition a reduction in herbicides would benefit the environment and improve biodiversity. However, until an effective alternative has been developed, chemical weed control will remain the standard for vegetable growers. One approach to limiting herbicide inputs has been to apply single or sequential sprays of reduced doses of herbicide.

Application of herbicide at low rates can be very effective because the full-recommended doses are calculated to ensure reliable control of specified weeds under a range of conditions. However, if a lower rate of herbicide is applied, less-susceptible individuals amoung weed species normally controlled may survive and set seed.In addition the reduced dose of herbicide may remain effective for only a short time, and late-emerging seedlings may also survive. There is a danger that prolonged use of this strategy may lead to higher inputs being needed in the future to control the weeds that have developed incresed tolerance. Once tolerance has developed within a population it is likely to persist within the gene pool of the weed seedbank.

The project aims to test the hypothesis that the strategy of using reduced rates of herbicide will result in increased herbicide tolerance in natural weed population and , in particular, amoung normally susceptible species. In field and glasshouse studies the herbicide tolerance of selected weed species in naturally-occurring weed populations will be measured initially and after repeated annual applications of low-rates of herbicide during the project period. The effect of repeated herbicide use on the composition of the visable weed flora would be monitored on the field plots. Each year, the level of herbicide tolerance will be measured in the progeny of selected species. Seed collected from treated and un-treated plants will be sown in the glasshouse and the response to different doses of herbicide monitored. The weed seedling emergence will be recorded each spring to determine whether any colour changes occur in the pattern of emergence following previous herbicide treatments.

The result will allow growers and policy makers to make informed assessments of the consequences for future weed control strategies that minimise herbicide use by reducing dose rates. If hypothesis is proved true, product labels and other advisory material can be amended to highlight the problem and provide guidelines to growers.
Objective
The project aims to test the hypothesis that the strategy of using reduced rates of herbicide will result in increased herbicide tolerance in the natural weed population and, in particular, among normally suscepitble species.
Project Documents
• Final Report : To determine the effect of strategies of herbicide use on the sensitivity of weed populations in field vegetable crops   (7429k)
Time-Scale and Cost
From: 1999

To: 2002

Cost: £173,696
Contractor / Funded Organisations
Horticulture Research International
Keywords
Farming              
Herbicide use              
Horticulture              
Vegetables              
Weed Control              
Weeds              
Fields of Study
Horticulture
Horticulture