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2005 Blackgrass Threat as Resistance Grows
Date added: 25/06/04 |
- 50% of most competitive weeds now showing significant herbicide resistance.
- Top 25% of producers spend half as much per tonne of wheat on herbicides as other growers.
2005 could be the year of a major Blackgrass resurgence unless crop producers plan their weed control policies very carefully warns ProCam technical director Dr. David Ellerton.
Speaking at the Procam 4cast Open Day at NIAB on Thursday 23rd June, Dr. Ellerton said the twin perils of increasing herbicide resistance and growers trying to take short cuts in weed control policy were potentially creating a real threat for next year.
Accessing crop records stretching back to 1979 through ProCam?s newly launched 4cast predictive agronomy system, he said whilst the number of active ingredients now available for weed control had grown from 22 to 35 over the last 25 years, herbicide resistance had escalated rapidly in the last five years.?With herbicide sales reaching a peak in 1996, our annual usage is now back to similar levels of 20 years ago but the most worrying feature is growing herbicide resistance. Even the mainstay chemical groups such as SUs and Fops are susceptible.
?We now have situation where 50% of the most competitive weeds are now showing significant signs of resistance,? he explained. ?With Mayweed now showing signs of resistance, we now have 6 out of the 12 most injurious weed species with significant resistance ? and it?s growing.?
In areas of high risk, both appropriate pre-drilling and pre-emergence treatments are critical and growers should practice a combination of both cultural and chemical controls within a field specific policy.
?Our 4cast data consistently shows that crop yield response to herbicide input is flat, so unlike fungicides there is no yield advantage to using more than you have to. The herbicide rule is use as much as necessary but as little as possible.?The top 25% of producers by crop yield and margin in fact spend on average £3/tonne on herbicides and the bottom 25% spend £6/tonne.
?The message is clear,? Dr. Ellerton says. ?Stay on top of your herbicide policy, don?t miss critical timings and don?t try and cut back on dose rate ? it will only cost more in the long run as our data clearly shows.?
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