Exploding populations of herbicide-resistant grassy weeds and broadleafs such as field poppy have triggered reluctant interest among UK farmers in integrated weed management.
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| A recent UK review found control of blackgrass using seven different non-chemical methods ranged from 20 to 80 per cent. -- Photo courtesy Oregon State University, Larry Burrell and Jed Colquhoun photo collection |
And, encouraged by EU legislation designed to reduce the volume of applied herbicides and other pesticides, researchers are also looking at cultural options.
The effectiveness of these alternative practices is limited, however, as demonstrated by one recent review in the UK.
Reported at Bayer's crop resistance conference in Miami this week, the review revealed that from seven non-chemical methods examined, control of black-grass (Western Europe's worst grassy weed) ranged from 20 to 80 per cent. Even at the top of that range, those control levels would be considered unacceptable in a herbicide registration application.
As well, the technology was often found to be more costly than herbicides, and results were highly variable (and sometimes worse than useless).
It was pointed out that cultural control measures gave better results when more than one were used simultaneously. Possible strategies include crop rotation, spring-seeded crops (where fall seeding is the norm), cultivation including plowing, delayed planting, fallowing, and higher seeding rates.
These measures can be enhanced in integrated weed management programs that include herbicides, even if the herbicides are less than fully effective.
But it's easy to see why farmers would far prefer a single herbicide application that controls all weeds present in a field.