Slow weed control after coldest spring for 50 years

Amenity managers may experience a delay in effective weed control this spring due to the extreme weather conditions, but patience and best practice will achieve the usual excellent results, says Monsanto.

Following a long, cold winter the poor conditions have just gone on with snow and overnight frosts throughout the spring of 2013, resulting in marked changes to the expected performance of glyphosate herbicides.

Monsanto produces the market leading Roundup glyphosate herbicide range and Technical Manager Manda Sansom explains that understanding how glyphosate works can prove very helpful in understanding how performance varies in different situations.

Glyphosate works by leaf uptake and translocation to the growing points in both shoots and roots. Here it blocks the biochemical pathway producing amino acids - the building blocks for protein - and causes a slow death by starvation.

Plant growth has been slow and a number of factors have led to slow or reduced performance compared to normal years and to users' expectations, she points out.

Plants need to be healthy and have sufficient leaf growth to absorb the glyphosate. Perennial plants like Thistles, Nettles and many grasses were late to emerge from winter dormancy and seed germination has been delayed due to cold soil temperatures.

Spraying by the calendar can result in herbicide being applied before sufficient leaf area has emerged. Even with good leaf coverage, low soil temperatures and high diurnal air temperature ranges resulting in slow plant growth mean visible symptoms can take up to 4 weeks rather than the expected 10-14 days. However, the end result will be the same.

For more information and guidance on optimum weed control using Roundup, please contact the Technical Helpline on (01954) 717575