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Winter cleaning with Simazine for vulpia (silver grass) and rat’s tail fescue control

By lesley - Posted on 26 November 2012

A winter cleaning spraying program can help control vulpia and rats tail fescue in improved permanent pastures.  Silvergrass and rat’s tail fescue in improved pastures are very competitive and can reduce carrying capacities by 25 to 50%.  Being so competitive means it restricts germination and inhibits clover growth.  Unfortunately these grasses hacve low nutritional value. 
The key to controlling these grasses is due to them having very few dormant or carryover seeds.  The approach that has been adopted in high rainfall grazing areas is to spray the pasture with a mixture of simazine plus paraquat, 6-10 weeks after the autumn break, once clovers have at least three trifoliate leaves.  The objective being to kill the large mass of silver grass and prevent the emergence of more germination for up to three months after the application without harming the clovers.
This approach has no adverse effect on clover or sown perennial pastures providing timing and rates are right, and have potential of improving pasture production significantly.  This method will also aid in the suppression of barley grass, brome grass and winter grass.
Justifying a winter cleaning program is quiet easy, if there is less then 10% silver grass then it is not necessary, however once we reach 20% silvergrass then this exercise can be justified.  The below flowchart will give you an idea of the management options available.  If you’re interested in a pasture cleaning program, then drop and see Daniell at Landmark to organize an on farm visit to discuss your options.
Management options