Thursday, 12 December 2019 09:10

World’s worst weed on the prowl

Written by  Mark Daniel
Velvetleaf with a blackened seed head. Velvetleaf with a blackened seed head.

With warmer weather bringing on forage maize crops in leaps and bounds, Waikato Regional Council is reminding farmers and growers to keep watch for velvetleaf.

It’s reckoned the world’s worst cropping weed, slashing crop yields by competing for nutrients, space and water. 

The seedlings grow vigorously up to 2.5 m high and can produce seeds viable for up to 60 years.

The national outbreak in New Zealand in 2016 was reckoned caused by imported fodder beet seed. 

Ongoing incursions in Waikato have been linked to infested maize crops and maize silage, unclean machinery moves and by stock that have eaten infected feed. The seeds can survive in maize silage and the guts of cattle, so can spread rapidly between farms.

Landowners and occupiers are responsible for controlling velvetleaf and should not allow any person to move, or allow to be moved, any velvetleaf propagules from a contaminated property.

And of concern to contractors is that no person may move, or allow to be moved, any cultivation or harvesting machinery that may be contaminated.

If a property owner suspects may have an infestation, they should contact pest plant staff on 0800 BIOSEC (0800 246732). Council staff will help develop individual biosecurity plans.

The council says plants that have not developed seed heads should be hand pulled, but if seed heads have formed, place a plastic bag over the seed capsules and flowers, tie firmly, then bend the stem in half, pull the plant, then place it in a second plastic bag. 

Where seed heads have blackened, a drop sheet should be placed on the ground to catch falling seeds. Then resort to the previous strategy and clean up any dropped seed. Soil may also need to be removed.

In pasture, if small seedlings are abundant, they should be treated with 2,4-D, but larger plants will need to be targeted individually with aminopyralid/triclopyr. 

In maize crops, use a pre-emergence application of acetochlor plus saflufencil to kill early weeds. After emergence, an application of topramezone, dicamba or mesotrione will help kill plants that may emerge later.

Tips for stopping the spread

Velvetleaf can spread by soil movement, stock feed and equipment such as diggers, crop harvesters and general farm machinery.

Farmers should protect their properties from velvetleaf and other serious plant pests by:

insisting all contractors practise good weed hygiene by thoroughly cleaning machinery before entering the farm

ensuring supplementary feed brought onto the farm is weed-free

ensuring manures, aggregates, soil and sand brought onto the farm is weed-free

checking feed crops before purchase to ensure they are weed-free.

More like this

$52,500 fine for effluent mismanagement

A Taupiri farming company has been convicted and fined $52,500 in the Hamilton District Court for the unlawful discharge of dairy effluent into the environment.

Featured

Trial shows benefits of spring nitrogen use

A landmark New Zealand trial has confirmed what many farmers have long suspected - that strategic spring nitrogen use not only boosts pasture growth but delivers measurable gains in lamb growth and ewe condition.

Eric Roy: Championing the pork industry

It was recently announced that former MP and Southland farmer Eric Roy has stepped down of New Zealand Pork after seven years. Leo Argent talks with Eric about his time at the organisation and what the future may hold.

National

Machinery & Products

JDLink Boost for NZ farms

Connectivity is widely recognised as one of the biggest challenges facing farmers, but it is now being overcome through the…

New generation Defender HD11

The all-new 2026 Can-Am Defender HD11 looks likely to raise the bar in the highly competitive side-by-side category.

» Latest Print Issues Online

Milking It

Buttery prize

OPINION: Westland Milk may have won the contract to supply butter to Costco NZ but Open Country Dairy is having…

Gene Bill rumours

OPINION: The Gene Technology Bill has divided the farming community with strong arguments on both the pros and cons of…

» Connect with Dairy News

» eNewsletter

Subscribe to our weekly newsletter