AgPest Alert: 1 October 2019

Consider forage crops to combat summer grasses

Region: Northland, Auckland, Waikato, Bay of Plenty

If your run-out pasture was infested with summer-active grass weeds last Summer, consider growing a forage crop for one or two summers prior to sowing the perennial pasture. This provides the opportunity to selectively spray the summer-active grasses and prevent weed seeds from replenishing the seed bank and infesting newly sown pastures. Forage crops will also disrupt clover root weevil populations allowing better subsequent establishment of young clover.

Prevent establishment of invasive weed Field horse tail

Region: Manawatū

Field horsetail (Equisetum arvense) is a very difficult to control perennial weed that regrows each spring/summer from an extensive underground root system.  Preventing establishment is the best form of control.  Make sure your contractors’ machines are clean and ask where the machines have been.

This root system comprises actively growing rhizomes that can penetrate to more than 1 m in depth, from which green fern-like fronds grow each year. Attached to the deeper rhizomes are small tubers which remain dormant while the rhizome stays alive. Upon the death/decay of the rhizome, or when it becomes detached due to cultivation or other means, the tubers are able to produce new plants.

Clover root weevils may reduce N fixed by clover

Region: All NZ

In established pastures with high levels of clover root weevil, the clover may be adding little in the way of nitrogen to the pasture and compensatory nitrogen applications may be required.

Ordering grass seed? Select endophyte.

Region: All NZ

When ordering grass seed select suitable endophytes and check that the endophyte you select has been assessed in the grass variety you order. In ryegrass, AR1 and AR37, and diploids with NEA2, will protect against Argentine stem weevil, AR37, Endo5 and NEA2 against black beetle and AR37 against porina. See DairyNZ Pasture Renewal Guide for a guide to endophyte selection.

Endophyte levels in the seed should be at least 70% and have been assessed in the last 3 months.

Look for slugs when direct drilling

Region: All NZ

If direct drilling new pastures or crops check for slugs as these can devastate establishing seedlings. An application of slug pellets may be required, or control may be achieved by heavy stocking rates.


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