AgPest Alert: 7 May 2020

Inspect young pastures for grass grub & porina

Region: Bay of Plenty, Waikato, Gisborne, Hawke’s Bay, Taranaki, ManawatÅ«, Whanganui, Wellington, Nelson, Tasman, Marlborough, Canterbury, West Coast, Otago, Southland.

In grass grub or porina prone areas check pastures for damage which is now showing. Grass grub damage is indicated initially by loss of clover and subsequently by patches of pasture turning yellow and later becoming soft underfoot. Porina damage initially appears as small (approx 5 cm dia.) areas of bare ground. Both pests should be controlled as early as possible to maximise returns and protect long term pasture production and quality. Although heavy rolling or high stocking rates may provide some level of grass grub control conventional insecticide (diazinon) may be the only recourse. It is now generally too late to obtain good control of porina using diflubenzuron, although caterpillars from late February/March flights in the North Island and the South Island West Coast are still susceptible.
In most cases, porina control now needs to be by conventional insecticide.

Manage broadleaved weeds by applying herbicide

Region: All NZ.

Check new pastures and apply herbicide as necessary to control broadleaved weeds (6-8 weeks after establishment).

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