Measurements to reduce insects in processed spinach

There are complaints about insects in Dutch organic spinach. Within this project, measures are formulated in order to decrease the amount of insects in this product.


Spinach - but also other leafy greens - has to do with a quality problem: insects in processed products. The Netherlands is leader in organic growing spinach in the EU. The quality of the spinach is good. An insect is sometimes found in processed products. Any complaint about the quality is one too much.  Customers have an urgent demand for quality improvement at this point of view.

The purpose is to formulate measurements improving the quality of spinach by reducing insects in processed spinach. The quality will be improved, focussing on the reduction of insects numbers in processed spinach. The whole chain is involved in this study from grower to processor.


In a spinach field many insects may be seen, more than 127 different species in three years were counted in Germany. The silver Y moth Autographa gamma (L.) (Lepidoptera: Noctuidae) caused the most problems. Also ladybirds and other beetles causes complaints. The big problems with the silver Y moth in the Netherlands are relatively new (from 2006). Before 2006 this insect was observed in much lower densities. The past 10 years, Within the spinach chain we figured out the opportunities for improving the quality of spinach. Possibilities are:


  • The largest numbers of silver Y moth are observed in July. Earlier sowing and harvesting (for July) will result in less silver Y moth in the fields and fewer in the final product. Sown spinach mid-April gave the least problems. Possibly by breeding the sowing date may be pushed forward again.
  • By signalizing during the season  the development of insects are followed, so that any surprises do not occur.
  • If the temperature in a spinach crop is measured, this can be used in a growth model evaluating the silver Y moth. Still the growth model has to be further tested in practice.
  • Three to four weeks after sowing (spinach in the sixth leaf stage) the plants must be properly examined for the presence of small caterpillars. If these are present in large numbers, a crop treatment can be carried out.
  • Late sowing in autumn, spinach has fewer problems with insects than sowing in spring. It should be noted that the last two years the summers were not warm and wet so the quality of autumn spinach was in some cases disappointing.
  • The fertilization vinasse seems to result in fewer problems with insects, silver Y moths and beetles then manure like digital state, cattle slurry, pig slurry, cow manure and chicken manure.

Suction mouth part of the spinach harvester

Spinach harvesters have a suction mouth to catch insects. The effectiveness of these machines can be improved by:

  • Increase the suction power and  the length of the suction opening
  • The suction mouth on the back site (side of the harvester) slightly running through the crop.
  • Possible the frame with chains is hanging too close to the suction moth. Insects have hardly any time to react.

Processing optimization process

  • It is clear that an insect separator (wind tunnel) into the factory can remove large numbers of insects from the harvested product (e.g. Silver Y moth and beetles). However, there are large differences in effectiveness of insect separators for each factory. In addition, one insect separator causes more damage to the harvested spinach then another.