AgPest Alert: 3 March 2021

Direct drilling new pasture?

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.
Small weeds can be effectively controlled with herbicides which are soft on clovers but if the weeds get too large they can only be controlled with herbicides which also damage clovers.

Wanting to control Californian thistle?

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).

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 Wanganui, 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.

In grass grub areas inspect 2 & 3 year old pastures for damaging levels of grubs.

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

Northern North Island watch for clover flea damage to clover. and treat early if required to maximise effectiveness.

Region: Northland, Auckland, BoP, Waikato

Northern North Island watch for clover flea damage to clover and treat early if required to maximise effectiveness.

Tasmanian grass grub damage may be showing.

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. Large numbers have been observed in southern Waikato.

Due to dry weather the pastures are very open.

Region: Northland, Auckland, BoP, Waikato

Due to dry weather the pastures are very open. There may be a flush of weeds after the first rain- treat if severe.
Pennyroyal can also become dominant after a drought and would need to be treated with 2,4-D early in spring if a problem.

Plantain moth numbers are building up.

Region: All NZ

Plantain moth numbers are building up and may increase dramatically after rain if warm conditions continue. Check with agchem reps. for insecticide options.

In 2016 velvetleaf was found in many fodder beet crops.

Region: All NZ

In 2016 velvetleaf seed was introduced to NZ as a contaminant of fodder beet seed and planted in many properties throughout NZ. To date more than 250 properties have been found to be infested with this terrible weed. Six different lines of fodder beet seed have been identified as contaminated but there could be others that were not picked up. Similarly there may be paddocks where velvetleaf was present but not found. 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. Last year was a cool year and no velvetleaf was found in the SI but it was found at some NI sites. This year is much warmer and more velvetleaf is expected to germinate. 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, visit MPI or AgPest online or contact your regional council.

Weeds can be spread via imported hay.

Region: Northland, Auckland, BoP, Waikato

If importing hay from other farms / regions be aware of unwanted weeds- many weed seeds can survive in and be spread via hay. Record the areas where hay has been fed out and regularly check these areas for new weeds after autumn and late spring rains- get rid of unwanted weeds before they become established! If you don’t recognise a weed get it identified.

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