Oliver Moore: New techniques in war against rushes

Rushes are the bane of many an organic farmer’s life, says Oliver Moore.

Ireland is wet at the best of times, but organic farmers in the west and north west in particular, face extra challenges with rushes. In recent years, very variable weather patterns have included veritable seasons of downpours.

Anecdotal evidence also suggests that derogations are difficult for organic farmers to get even for a one-off spraying.

Rushes on farms means, simply, that there’s less grass available to livestock per acre, and sometimes a diminishing amount of grass available, each year.

The UK Organic Research Centre held a dedicated session on rushes at their recent conference. Consultant Ian Carnes said there are short term abatement type measures, as well as longer term control measures.

Rushes, with their “dense, deep rooting clumps” compete under the ground, so the quality of grazing (as well as the percentage of area available) reduces. High rainfall and corollary poor drainage are key determinants of rush susceptibility.

Carnes outlined a four stage plan for addressing rushes. This comprised:

* Soil, sward appraisal;

* Common rush control management programme;

* Improve competition from a more productive sward; and

* Implement an effective grazing and sward management programme.

This plan should be individualised to the farm and — in some cases — even to the field. Drainage, soil structure, liming and soil nutrient status are key to addressing the underlying soil issues.

Reseeding was described as possibly the “ultimate control strategy”. While each farm is unique, he pointed to a seed mix comprising four different rye grasses, as well as timothy, meadow grass, creeping red fescue and white clover.

With a light infestation, effective control can be maintained by hard grazing in the summer but avoiding excessive grazing in the winter; prioritising cattle over sheep and topping in the summer.

He also pointed out that it is, with increasingly wet summers, more difficult to make uplands productive.

As the ORC summary pointed out: “Effective control strategies are centred on the need to make conditions more suitable for a productive sward to compete with rushes, including improving drainage, deep ploughing, liming and re-seeding.

"The extent to which each of these can be employed depends on cost factors, soils and conditions and the farm’s agri-environment scheme.”

A practical example was given at the event. Dianne Horn, of Slack House in Cumbria, needed what was described as a major intervention to get her rushes under control.

This involved “deep ploughing and broadcast re-seeding, followed by cutting twice and hard grazing in summer. In combination these strategies brought good control, which was aided by using competitive species in the re-seed mix.”

Heavy rain after reseeding was cautioned about, however, as it can, literally, wash away much good work.

Another approach was outlined some time back at a NOTS event. NOTS — the National Organic Training Skillsnet — runs dedicated courses in Ireland for farmers on a range of topics, which can be attended by both organic and conventional farmers.

This course pointed to the relevance of early cutting of rushes, where “the frost can help kill up to 40% of what’s left”... “Another advantage of cutting at this time of year is that the sap has dropped and the rush becomes more brittle and easier to cut, using less fuel.

Surprisingly the advantage of cutting rushes is that they provide effective fertiliser as they contain 70% NPK value of farmyard manure, so the cut rushes can put humus back into the land and help boost grass growth.”

This suggestion has been greeted with a mix of support and cynicism by farmers. Conventional farmers however, can always fall back on the spray. For organic farmers, new techniques will have to keep emerging in the battle against rushes.