AgPest Alert: 1 May 2021

Grass grub damage will be showing up by now.

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

Grass grub damage is indicated by patches of pasture turning yellow and later becoming soft under foot. Pasture can be easily pulled back which is likely to reveal larvae feeding near the surface. 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, except for caterpillars from late February/March flights in the North Island and the South Island West Coast which are still susceptible. In most cases porina control now needs to be by conventional insecticide.

After the drought most pastures will be open to infestations of winter weeds.

Region: All of NZ

Strengthen pastures by undersowing or opt for complete renewal. Either way manage broadleaved weeds by applying suitable herbicide 6-8 weeks after sowing.

Black beetle now infest large parts of the North Island with damaging populations.

Region: Northland, Auckland, BoP, Waikato

Black beetle now infest large parts of the North Island with damaging populations occurring as far south as coastal parts of Manawatu and Hawkes Bay. Endophytes such as AR37, and NEA2 deter the adult beetle from laying eggs in spring and thereby reduce larval numbers. To maximise the effects of endophyte, it is important that infection levels are high in ryegrass or tall fescue and that the pastures are not infested by other host grasses such as kikuyu or paspalum.   See DairyNZ Pasture Renewal Guide  

Tasmanian grass grub damage may be showing.

Region: Gisborne, Hawkes Bay, Waikato, Manawatu, Canterbury, Otago

Unlike the NZ native grass grub, Tasmanian grass grub live underground and feed on herbage. Damage appears areas of poor pasture growth. Check pastures particularly around stock camps and assess numbers to determine if insecticidal control is warranted. This pest is now occurs throughout much of New Zealand.

Social tagging: > > > >

Comments are closed.