AgPest Alert – 4 June 2019

Insecticide may prevent long term pasture loss to grass grub and porina

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

Grass grub and porina damage will now be evident in most areas. Grass grub damage is indicated initially by loss of clover and subsequently by patches of pasture turning yellow. At this time of year, these patches become soft underfoot and are prone to pugging.
Porina damage will show as bare areas of pasture often with only weed plant species present. Conventional insecticide is the only control option likely to give control of either pest. By now production losses have already occurred but treatment may save the affected pastures. Porina damage, especially in Hawkes Bay, Taranaki, Wairarapa and Manawatu from caterpillars arising from late February/March flights, may only now be becoming apparent. Careful consideration needs to be given to control options as spring growth may occur before damage becomes such that plants are lost from pastures.

Check pastures for Tasmanian grass grub damage

Region: Gisborne, Hawkes Bay

In areas where Tasmanian grass grub can be a problem, damage may be seen. Check pastures, particularly around stock camps, and assess numbers to determine if insecticidal control is warranted.

Make preparations for winter spraying of weeds

Region: All NZ


Make preparations for winter spraying of weeds if required. Scout paddocks and map infestations of weeds such as ragwort, thistles. Develop strategies for ongoing management of weedy areas, e.g. grazing, set-aside, spraying, nutrient or lime applications etc.

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