Technical


Herbicides are relied on to control weeds at sports facilities and in ornamental areas, but care must be taken to minimise the risk of resistance. Plan applications for when the weeds are most susceptible to herbicides


rigidum, Lolium perenne and Lolium perenne var. multiflorum.


Fleabane, or Conyza resistance has developed in amenity situations, including railways and roadsides, as well as in perennial crops. Ryegrass resistance has occurred predominantly in perennial crops and also in arable farming.


The first occurrence of ryegrass resistance was in France in 2005 and, like Conyza, it was in an orchard. It was also found in Israel in 2007 and Italy in 2008 on arable land. It has not been found in specific amenity situations, however many perennial crop situations mimic practice in amenity.


It is also worth remembering that Groundsel developed resistance to the amenity herbicides atrazine and simazine back in the 1960s and Annual Meadow‐grass has developed resistance to glyphosate in other parts of the world.


Best practice


Glyphosate use in industrial and amenity areas should always follow Good Plant Protection Practice as the basis of the weed management strategy (EPPO Standard PP 2/1(2),2003) and should be included as part of an Integrated Weed Management Strategy as required by the UK National


Action Plan implementing the Plant Protection Products (Sustainable Use Regulations), 2012.


Continued use of glyphosate several times each year over many years in conjunction with the loss of alternative residual active ingredients, increases the theoretical possibility of resistance, and a Resistance Management Strategy should be in place.


Resistance Management Measures


1) Use of the correct dose rate of a reputable approved glyphosate product which has been manufactured to WTO standards. Do not use lower rates than are


PC JUNE/JULY 2018 I 133


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