Improving the management of insect contaminants in processed leafy vegetables (VG12108)

This is a final research report from Hort Innovation’s historical archives. Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.

What was it all about?

Insects are potential contaminants of processed leafy vegetables. Pest and beneficial species, in both the juvenile and adult stages of their life cycles could easily become unwanted contaminants if they made their way from the field into the final product, and to the end consumer.

Insect contamination had resulted in rejections and lost sales for growers, added cost for processors and bad publicity for retailers. Ensuring year round supply of insect free produce was a difficult challenge. The main products affected were baby leaf spinach and coral leaf lettuce. The major insects causing problems were: moths, soldier files, Rutherglen bugs and ladybeetles.

The approach was to first review published research on controlling insect contaminants in leafy vegetables crops availabe at the time. Then a range of measures were evaluated in field trials with the aim of reducing insect contaminant levels. Trials included insect deterrents and attractants, floating row covers, and harvester modifications intended to remove insects at harvest. In addition, trials were conducted in the factory to assess the best methods of removing insect contaminants along the processing line.

The most effective methods for reducing the level of insect contaminants were the use a moth attractant plus a knockdown insecticide, light traps to reduce moth populations in a radius of 100m, harvester modifications to remove insects at harvest and floating row covers to exclude insects from baby leaf spinach crops. In the factory, rotating drums removed most of the insect contaminants and dead moths were much easier to remove than live moths.

The key results were put into a 4-page grower factsheet which was distributed to all vegetable growers. Four regional workshops were conducted (Qld, Vic and WA) where 70 growers and agronomists were trained on the techniques. The workshops were run in conjunction with the national Integrated Crop Protection extension project (VG13078).