4 minute read
Weed battle highlights importance of cleaning
Waikato farmer Cameron Berry had never heard of velvetleaf when he got the call from his farm advisor: “I think you better come to the paddock. We’ve found something you won’t like.”
That was 2018, the beginning of a management and eradication programme that has echoed across the Waikato and New Zealand. It emerged that the velvetleaf seed had arrived on an unaware contractor’s dirty machinery while the paddocks were being leased. Five years later, Cam has velvetleaf management down to a fine art. “There are three main things you need to do once you’ve spotted velvetleaf,” Cam says. “Tell the regional council, work with them on the chemicals available and then perfect your timing of postemergent spraying.” Waikato Regional Council quickly came in to support Cam. Having knowledge of the outbreak across the region, its pest plant team, led by Biosecurity Officer Heidi Pene, could work together on the best way to manage the incursion on Cam’s farm. “I was really lucky because we caught it in the early stages. Heidi and her team were great. It can be a bit unnerving when four council utes come driving up but at the end of the day it’s not your fault and they’re just there to help,” Cam says. “That first year they were tall enough that six of us went around and pulled them out by hand. It was a big job doing it three times across four paddocks. Fortunately, the infestations were concentrated on the outside rows of the paddock.” Now aware of what to look out for, Cam works with his contractor, Neven Granich, who spends up to an hour with an air gun making sure his machinery is clean before he moves off-farm. “When harvesting, we systematically work through the 28 hectares of maize, leaving the paddock that’s been infected with velvetleaf as the last one to harvest. Neven is an incredible man. It’s easy for a contractor to want to move on quickly to the next job but he does it right.” Connecting with the right people is key, Cam says. He worked closely with the regional council on a management plan and with his contractors to make sure the spraying is effective. Velvetleaf requires pre-emergent and post-emergent treatment. Cam’s plan needed a good cover of 200 litres to the hectare, which meant having the spray contractors on board. “Once you let them know that there’s a problem, what you’re doing and what you’re using, they’re happy to spend a bit longer making sure the coverage is right. “You really need to do a pre-emergent spray. It’s the post-emergent spray that’s a big expense. So for cost-conscious farmers, spraying around the outside will help. Early detection or prevention is much cheaper.”
| Cameron Berry worked closely with the regional council on his velvetleaf problem. | Wink the velvetleaf detector dog is on the case.
Cameron Berry
Timing is everything when you’re postemergent spraying, Cam says – leaving spraying until all the dormant seeds have emerged from the ground but not so long that the maize has grown high enough to protect the velvetleaf seedlings from the spray. He’s got a simple trick to live by. “When your plants are almost Red Band height, spray then. Especially when the maize is growing fast. A handspan high is too early and you’ll end up with new velvetleaf seedlings coming through.” He says the ideal spraying would be if your contractor has a dropper on the spray unit so they can get them a bit taller and spray underneath the maize to the velvetleaf below. When the maize is fence height, Cam walks around the outside rows and anything left can be pulled by hand. In 2020 Heidi suggested trialling a new mechanical method, a strip till cultivation programme on the paddock with the most velvetleaf. Cam admits he was a bit cautious at first. “It’s a soil management technique that creates less stirring up of the soil. It means the dormant velvetleaf seeds aren’t mixed around as much in the soil and are spread far less. Our contractor Neven bought a strip till cultivator and the result was a lot better than I expected.” The maize in the trial paddock has seen a better yield and noticeably less velvetleaf. “It’s also better for the environment,” Cam says. “It was such a successful trial that we’re starting to use the strip till in other paddocks now too. “We had the velvetleaf detector dog come run around before Christmas when the maize was knee height. The dog just sits down next to a plant if he finds it. It’s quite cool and opportunities for detection like that are another good reason to keep close contact with your regional council and Biosecurity New Zealand.” Because velvetleaf seeds can remain dormant in the soil for so many decades, many regions are focusing on longterm management for the unwanted organism. Knowing what to look for, declaring it to council or to Biosecurity New Zealand’s 0800 80 99 66 hotline and ensuring machinery is clean before entering and leaving the farm are key to preventing the spread. “I’m paranoid about it now,” Cam says. “I go past fields and I can’t help keeping an eye out for it. I reckon we’re winning on our farm but to keep things that way we’re staying on top of it every year.”
