AgPest Alert – 5 March 2019

Direct drilling new pasture? Watch for slugs and grass grub.

Region: All NZ

If pasture establishment by direct drilling is going to be used, check those pastures for slugs and grass grub as even low numbers can devastate young seedlings of pasture or crop plants. Wet sacks can be laid in the paddock, slugs will shelter under these and be seen on the pasture surface if inspected after 2-3 days – more than 2 slugs per sack could result in seedling loss. To detect grass grub dig at least 10 15 x15 cm holes 15 cm deep and search the soil – as few as 1 grub/hole could cause damage.

Control Californian thistle by mowing in rain

Region: All NZ

Mowing Californian thistle during rainfall can improve control of this weed by 30% as compared to mowing during dry weather. Best time to do this “wet mowing” is in February/March when the fungi thought to be responsible for this effect are producing spores on the thistle. The effect is likely to be greatest if some members of the thistle population to be mowed are showing signs of disease (wilting, yellowing, dieback).

Select endophyte when ordering grass seed

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, 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 or the cultivar selector on Dairy NZ’s Forage Value Index.

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

Late flights of porina occurring in lower North Island

Region: Hawkes Bay, Taranaki, Manawatu, Whanganui,  Wellington

Late flights of porina may occur in the North Island, especially in Hawkes Bay, Taranaki, Wairarapa and Manawatu. These could result in damage appearing in June in infested paddocks. Look to apply diflubenzuron in late April-mid May.

Inspect grass grub areas for damaging levels

Region: Bay of Plenty, Waikato, Gisborne, Hawkes Bay, Taranaki, Manawatu, Whanganui, Wellington, Nelson, Tasman, Marlborough, Canterbury, West Coast, Otago, Southland.

In grass grub prone areas 2 and 3-year-old pastures should be inspected to determine if potentially damaging levels are present. Early treatment will offer most protection and maximise returns from the cost of intervention.


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