Couch identified - and spreading where Tradescantia was removed

The roadside holds a little Couch grass (Cynodon dactylon), observed in March and suppressed with Tradescantia, then observed in September emerging nearby where Tradescantia had been removed. (You can switch between the two linked Observations using the "Linked Observation" Field at lower right of each observation).

This grass was seen in March around the base of one harakeke at the roadside, and in September, when wet ground allowed a short section of rhizome to be pulled up and examined. Though the leaves are soft and fine, we find the rhizomes unbreakable.

It is within 20-30m of a widespread invasion in 1999 which followed virtual eradication of kikuyu for tree planting. The 1999 invasion was presumably mulched or otherwise suppressed until shaded out by the close-planted trees. The current occurrence is likely a remnant which survived at the roadside beyond the shade, where it is presumablylimited by the deep dense Tradescantia all around it, and by mowing of the grass verge. In March it was flourishing at the base of the harakeke where mowers cannot reach.

This occurrence is now being suppressed (and hopefully eventually rotted) with Tradescantia in front of the harakeke, but has emerged nearby where Tradescantia was removed.

Plan: Restore deep Tradescantia as mulch where this is emergent, and monitor.

Posted by kaipatiki_naturewatch kaipatiki_naturewatch, September 11, 2019 03:32

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