Redroot

Mature redroot plants showing
seedheads.

Provided by Dow AgroSciences.

Redroot is the name given to a group of 3 closely related Amaranthus species:

• Amaranthus hybridus
• Amaranthus powellii
• Amaranthus retroflexus.

A fourth species that is similar to redroot is Amaranthus viridis - purple amaranth.

Also commonly referred to as "Amaranthus", these weeds are widely spread throughout New Zealand, and get their name from the reddish colour towards the base of the plant and tap root. They are commonly found in arable crops and can grow up to 1 metre high. All 4 species are summer growing annuals that normally flower between December and February. Flowers are small and spikey and have many short laterals. Seedheads are commonly up to 200mm long and droop downwards from stems. Main stems form numerous short leafy laterals. Leaves are variable in size, oval shaped and usually green, although they turn red in autumn.

How to control Redroot

Broadcast spraying:

There are a number of options for the control of this weed in pasture and other situations.

Redroot seedling at
ideal time to spray.

New pasture:
Select* and MCPB Herbicides will provide excellent control without injury to new grass and clover.
Select - 3-4L/ha at the seedling stage, useful suppression at later stages.
MCPB - 4L/ha but must be treated at the seedling stage.

Established pasture:
Maestro* and Pasture-Kleen* Xtra Herbicides can be used. Some temporary suppression of clover may occur.
Pasture-Kleen Xtra - 0.75 L/ha for seedlings or 1.5 L/ha for small plants
Maestro - 1.5L/ha on actively growing weeds at the 4-6 leaf stage.

Spot treatment:

Young redroot plant showing
emerging laterals.

Tordon* Brushkiller or Tordon MAX can be used as a spot spray to control this weed in pasture, established turf and waste areas. Clover will be temporarily removed form the sward.

Fodder brassicas:

In fodder brassica crops, Tordon MAX at 1.5ltrs per ha with Uptake oil provides good suppression of this yield suppressing weed without damaging your crop.

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