AgPest Alert: 14 January 2021

Aphids, diamondback moth & white butterfly caterpillars in brassica crops increasing in numbers. 

Region: All NZ

Keep an eye on aphids, diamondback moth caterpillars and white butterfly caterpillars in brassica crops. With warm summer temperatures these can increase quickly. Treating these pests before high numbers occur will provide greatest economic return.

Watch for plantain caterpillars and moths

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

Plantain moths and caterpillars populations maybe high or building up. Apply insecticide early to prevent damage occurring

In the northern North Island damage from black beetle larvae may be showing

Region: Northland, Auckland, BoP, Waikato

In the northern North Island damage from black beetle larvae may be showing. Unfortunately little can be done to prevent this. Adults are deterred by some endophyte- infected grasses which will reduce egg laying and larval numbers. See DairyNZ Pasture Renewal Guide

Watch for Tasmanian grass grub beetle flights

Region: Gisborne, Hawkes Bay, Canterbury, Central Otago

Watch for Tasmanian grass grub beetle flights, large numbers of beetles flying may indicate potential damage from the larvae in autumn and winter.

Flights of porina moths

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

The early flight of porina moths has passed but the second significant flight is about to occur in the South Island and could take place anytime between now and the end of February. Further flights may occur in March in the North Island. In areas that experienced an early (October/November) porina flight, mid-January to mid-February is the optimal time to be applying diflubenzuron.

Argentine stem weevils will increase in significance over summer

Region: All of NZ

Argentine stem weevils increase in significance over summer. Be aware that seedling grasses, even those infected with endophyte, are very susceptible to damage from this pest if numbers are high. This also applies to cereal and maize crops. Coated seed or pre-emergence insecticide application can prevent damage.

Clover root weevil damage

Region: All of NZ

Clover root weevil adults are abundant and damage to clover leaves will be obvious in most areas. Unless severe this is not significant damage and does not mean the biocontrol agent is absent. 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 overgrazed.

If you have grown fodder beet over the past 3 years

Region: All of NZ

Velvetleaf seed was introduced to NZ as a contaminant of some fodder beet seed and planted in many properties throughout NZ. Therefore, if you have either grown fodder beet or received fodder beet onto your property you need to be vigilant and keep an eye out for this weed and do not let it establish on your property. Velvet leaf is declared Unwanted Organism by MPI and occurrences must be reported and dealt with. For more information phone the MPI hotline 0800 80 99 66 or go to MPI or go to AgPest, or contact your regional council.

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