Biosecurity vital to halt weed
Waikato farmers will need to ramp up their biosecurity practices to stop velvetleaf spreading throughout the region this summer.
The warning from local and central government comes nearly four months on since the invasive weed was discovered in a fodderbeet crop and then later in maize crops around the region.
If left unchecked, farmers risk facing a substantial problem containing the plant over the long term, the Ministry for Primary Industries’ Catherine Duthie said at a recent velvetleaf information meeting at Elstow near Te Aroha.
A single, well-grown plant produced as many as 17,000 seeds in pods that were easily spread if broken.
‘‘It’s estimated that unmanaged, it can reduce the yields of arable crops by 30-40 per cent,’’ she said.
The Waikato Regional Council inspected 101 Waikato farms since it was discovered in late April this year and found the plant on 29 farms throughout the region, mostly in the Te Aroha-Waihou area.
There are another 70 at-risk farms that the council will be following up in spring.
The response in Waikato was different to other regions because of its discovery in maize crops, Waikato Regional Council pest plants team leader Darion Embling said.
Waikato needed to consider what value it placed on its maize industry because landowners faced a huge cost if the invasive weed was left to grow.
‘‘If we don’t do anything, the best-case scenario 10 years from now is a 30 per cent loss of income for the arable industry. The arable industry in New Zealand is worth $1.5 billion so you are looking at $500 million per year this country could lose.’’
Dealing with the weed also cost the regional council alone more than $200,000 last year.
Velvetleaf seed will germinate as soon as the weather warmed and he expected it to begin appearing from October onwards.
Farm owners should dispose of any velvetleaf plants found before the plants had set seed. If the plant had gone to seed, it should be double-bagged around the seed pods to prevent spillage and disposed by deep burial, such as in an offal pit, Duthie said.
‘‘What we are trying to tell people is that good on farm biosecurity will help reduce not only the issues from velvetleaf but from all other pests as well.’’
Farmers also had a legal requirement under the Biosecurity Act not to move velvetleaf off their farm if discovered. Contractors or other workers needed to be notified when entering the farm that velvetleaf was present and take appropriate measures when leaving the farm to wash down their equipment to ensure it did not spread.
In turn, contractors needed to ask farmers if velvetleaf was on their farm this season and follow good machine hygiene.
It can also be transferred around a farm or between farms by livestock eating fodderbeet or maize silage, swallowing the seed and excreting it.
Any paddocks known to contain velvetleaf also had to be monitored for the next five years.
A good on farm management plan had to be adopted. This was essential because it allowed farmers to work out options of what they can and cannot do on affected paddocks, Duthie said.
It was an annual plant and if farmers removed it before it seeded, it no longer posed a problem. That was why the MPI had urged farmers to thoroughly check their crops and remove any velvetleaf plants to prevent the next generation being removed, Duthie said.
‘‘If you are regularly checking your field and removing all those plants prior to them setting seed, then you reduce the problem exponentially.’’