Meeting at Upper Pinkerton to discuss flooding 4th March 2020

On 4th March Frances, Irene, Nathan (Western Water) and Daryl met at Pinkerton to discuss weeds in Upper Pinkerton.

Stuart Boardman of contractor Haas and Grey reported that irrigation water had breached the boundaries and flooded into Upper Pinkerton, creating the growth of weeds. There was concern that the biodiversity of Upper Pinkerton would be adversely affected by the excessive weed growth.

The suggestion was made that the area could be grazed to remove the weeds.

We walked through the affected area to find that exotic weeds had proliferated in the flooded area.

However, we were amazed to see the proliferation of Microlaena (Weeping Grass) here among the weeds, following the flooding. The Redleg Grass and Windmill Grass are also seeding prolifically.

The Redleg Grass is especially valuable due to its very deep roots (at least 1.5 metres deep).
We are keen to see that the native grasses have an opportunity to fully develop & ripen, as this will greatly contribute to the biodiversity of Upper Pinkerton.

Also, the Plains Joyweed (Alternanthera sp 1) is growing well & flowering, especially in the flooded area. We are keen not to have this rare grassland plant grazed before it has the chance to set seed.

As we have not seen much Weeping Grass here in Upper Pinkerton we are eager to allow the seeds to mature & form a seed bank in the soil.

After discussion following our walk in Upper Pinkerton we decided that would like to see grazing here deferred until late winter or spring. The sheep may not be too keen anyway to eat the exotic grasses at this time as these are now quite tall. If they are unwilling to eat the tall exotic grasses then they may well eat the shorter natives that are now seeding.

There will be ample opportunity later in the year for sheep to graze the weeds in spring, without damaging the native grasses.

Excessive weed growth due to periodic irrigation overflow is something we have learn to deal with over the years. Not a great disaster in the overall scheme of things.