Growing Futures

Controlling a vegetable pest

Controlling a vegetable pest

Managing brassica pest reduces growing costs and yield losses

Around 70 million tonnes of vegetable brassica crops such as cabbages, broccoli and cauliflower are produced globally each year for human consumption, with the majority grown for the domestic market. New Zealand produces 92,000 tonnes of vegetable brassicas, with domestic sales of $80 million and a small export market with a value of $2.7 million. In addition, around 300,000 hectares of forage brassicas, including kales, rapes and turnips, are planted each year as feed for New Zealand’s dairy and meat industries.

The diamondback moth (DBM) is the most important insect pest of brassica crops worldwide. At its worst, it can lead to total loss of a crop. There is a global effort to develop new ways of managing the pest, as the moth is developing resistance to many of the insecticides currently available.

A programme for control

Since 2000, an integrated pest management (IPM) programme for controlling the diamondback moth in New Zealand has been available for vegetable brassica growers, with an updated manual published in 2009. This manual provides methods for monitoring pest populations and advice on the insecticides that should be applied at different points in the season, to protect beneficial insects and to limit residues at harvest, should a defined threshold be exceeded.

The introduction of this IPM programme, now adopted on more than 70% of the New Zealand vegetable brassica crop, has stopped insecticide resistance development in the diamondback moth population, despite reports of continuing development in many other parts of the world. It has also led to a significant decrease in the amount of pesticide applied to brassica crops. The adoption of the IPM programme is estimated to have had an annual benefit of $2 million, in reducing yield losses and growing costs for the grower and in reducing costs for the sector associated with insecticide resistance in the moth.

Development of the IPM brassica toolkit was funded by the Ministry for Primary Industries’ Sustainable Farming Fund, Horticulture New Zealand and Plant & Food Research, with support from the agrichemical industry.

Created: September 2014

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