A small beetle that eats vine leaves, shoots, and buds is becoming a big problem in organic Marlborough vineyards, a vineyard manager says.
Kono Beverages Marlborough group vineyards manager Mondo Kopua said the brown beetle, known in its early stages as grass grub, was normally kept under control by spraying insecticides. But as more vineyards become organic, vineyard managers are having to look for alternative ways to control the pest.
Starting next week, Kono Beverages, Lincoln University professor Steve Wratten, from the Bio-Protection Research Centre, and PhD student Mauricio Gonzalez Chang will dig holes and set traps in a designated area to study the life cycle of the beetle.
Kopua said the project, funded by a Callaghan Innovation Grant, would focus on breaking the beetles' life cycle while they were still grass grubs.
"If you can reduce the population in the ground then, theoretically, you are not going to have so many beetles flying."
No-one had been able to "accurately forecast and predict" when their flights would happen, so the research would focus on their flight patterns as well, he said.
The beetles caused most damage in spring, when buds started to grow, Kopua said.
"Depending on numbers and the level on infestation, it can strip the leaves that are just starting to grow, and when you get small buds that are developing, they nibble through those too.
"They also ringbark them, so that means that they will never turn into a flower or turn into a bunch [of grapes]."
As a result, yields were affected, Kopua said.
"Your primary shoots and your primary buds are the most fruitful, so if they get damaged the natural course is to produce a second one, but often this second one might lead to smaller or fewer bunches."
Kono Beverage's pinot noir and chardonnay vines in the Awatere Valley were the worst affected, Kopua said.
Wither Hills and Rock Ferry Wines would also trial some of the research practices in their vineyards.
Rock Ferry viticulturist Kurt Simcic said they would follow the project's progress closely as they were having "big issues" in their organic vineyards on Hammerichs Rd.
"We have high numbers of brown beetle on that block. It's a big issue, so we are always looking for an alternative solution."
Their pinot and chardonnay blocks have been hit hardest, but some of their sauvignon blanc blocks were also affected, Simcic said.
"You get less fruit because they get to the shoots, so it makes things difficult and it slows the vines right down."
They were currently using a trial-and-error system to get rid of the beetles, so they were looking for a product that would have definite results, he said.
If the research provided a solution, it would benefit conventional vineyards as well, Simcic said.
- The Marlborough Express
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