AgPest Alert: 1 November 2021

Clover root weevil present in most areas.

Region: All of NZ

Clover root weevil will be very obvious in most areas –U shaped notches at the edge of clover leaves show adults are present. The presence of larvae may be indicated by the pasture appearing nitrogen deficient. While control is generally not an option careful management of clover will help maintain pasture quality. Additional nitrogen may need to be applied to pastures and clover should not be over grazed.


Consider Argentine stem weevil in pasture/crop establishment.

Region: Northland, Auckland, Bay of Plenty, Waikato, Gisborne, Hawkes Bay, Taranaki, Manawatu Wanganui, Wellington

Argentine stem weevil is building up in the North Island and will need to be considered in pasture and crop establishment. Insecticide coated seed may be a viable control option and insecticide application can provide temporary relief from this pest and allow seedlings to establish. Argentine stem weevil is a significant threat to seedling grasses, even those infected with endophyte, cereals and maize crops. See DairyNZ Pasture Renewal Guide for a guide to endophyte selection.


Check sunny slopes for Chilean needle grass with its reddish purple seed heads.

Region: All of NZ

Chilean needle grass will become evident in pastures in November-December. Keep an eye out for the reddish purple colour of the seed heads when they first emerge. Each seed has a 7 cm long awn (bristle-like tail). This grass is most likely to be found in pastures on north/west-facing drought-prone slopes but may be present in contaminated stock feed / hay.  If you suspect that you have it, please contact your local council biosecurity people for identification and management advice immediately.


Look for and note porina flights as these can indicate when to adopt control measures later if required.

Region: Taranaki, Manawatu Wanganui, Wellington, Nelson Tasman, Marlborough, Canterbury, West Coast, Otago, Southland


Check your sunny slopes for Chilean needle grass in November and December.

Region: All except West Coast of South Island

Chilean needle grass will become evident in pastures during November and December as its distinctive purple-coloured spikelets, with their developing long-awned needle-sharp seeds, emerge from elongating flower stems. Details of this invasive grass can be found here on AgPest. This grass is most likely to be found in pastures on north/west-facing drought-prone slopes.  If you suspect that you have it, please contact your local council biosecurity people for identification and management advice.


Tasmanian grass grub beetle flights occurring.

Region: All of NZ

Tasmanian grass grub beetle flights occurring. This pest appears to be spreading and may appear in areas where it has not previously been seen. e.g. It is now present in Cromwell. The significance of this is not yet known. New observations can be reported to colin.ferguson@agresearch.co.nz


Be vigilant for new weeds which you have not seen before.

Region: All of NZ

In newly planted crops, scout for new weeds and weeds that have survived spraying with herbicides. Get these identified by sending photos to AgPest as they may be either a serious new incursion or have become resistant to herbicides. In either case it is important to get this sorted before they become established over large areas. Report weeds at www.agpest.co.nz/report


Watch out for Yellow Bristle Grass on the roadside, it is rapidly moving south.

Region: Canterbury, Marlborough, Nelson, Manawatu

Yellow bristle grass (YBG) is continuing to expand its range and is rapidly moving south into Manawatu and Canterbury. Watch for an upright grass with many compact, yellow-tinged seed heads appearing on the roadside. Take measures to stop it moving onto your farm. For more details see

http://agpest.co.nz/?pesttypes=yellow-bristle-grass

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