Floral fight against green terrorists

Posted On 22 Feb 2014
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FP3NEW ZEALAND: The university suggests there’s no need to alert the authorities, however. The horror is taking place at a more microscopic level, and it’s all for a good cause.

To promote biodiversity and reduce the use of pesticides, award winning food company, Snap Fresh Foods, has teamed up with Lincoln University to harness the pest-killing attributes of flowers. More to the point, the flowers are being used to attract the right kind of killer insects.

The company grows Asian baby leaf brassicas such as Mizuna, Tatsoi and mustards, as well as wild rocket, at its Rangiriri site just north of Huntly. A major issue for anyone growing these types of plants is leaf miner: the larva from a number of fly species which live between the upper and lower leaf surfaces. The leaf miner eats the leaf tissue in such a way as to leave distinctive trails. Notoriously difficult to control, leaf miner, while not affecting the yield, does undermine the cosmetic attributes of the leaf, resulting in a notable blemish which is undesirable to some consumers.

To combat this, Lincoln University’s Professor of Ecology, Steve Wratten, has teamed up with PhD candidate, Ryan Rayl, (sponsored through Callaghan Innovation) to explore ways in which particular flowering plants can be used to attract insects which feed off leaf miner, such as ladybirds and parasitic wasps.

“The goal of the project is to create strategically placed strips of various flower species among the cropped areas to provide pollen and nectar for insect predators with a taste for leaf miner; not to mention encourage the presence of particular parasites which live off the larva as well,” says Professor Wratten. “From these flowers the leaf miner’s insect enemies get the protein from pollen to help produce their eggs, as well as nectar for energy. The aim is to build up a ‘bank’ of predatory insects prior to growing the commercial crop.”

The flowering plants currently being evaluated for the project include the common garden flower, alyssum, buckwheat and phacelia, all of which have a proven track record in vineyards.

Snap Fresh Foods approached Lincoln University after hearing of their expertise in pest management through biodiversity. Director of Snap Fresh Foods, Ashley Berrysmith, says that, as well as the cost saving benefits from such an approach, the company’s ultimate goal is to move towards a sustainable horticultural enterprise, producing residue-free foods.

“It’s important to try to move towards sustainable, chemical free production if possible. Our vision for the company is to roll out a biodiversity model for pest control across the entire business,” he said. “This can only happen by taking a sound, scientific approach. Beyond the cost and environmentally friendly benefits of the project, however, having flowering plants throughout our plantations will add visual appeal and go some way to tell the story of what our company has always strived to be.”

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