4 march 2022
RHP wants to develop, in a substantiated manner, standards for residues in substrate raw materials. What does a residue do to a crop if it is present in a substrate? RHP wants to gain a good idea of that this year with additional plant response tests in a specific research project. How RHP-certified companies can send samples for this, they can read at My RHP.
At My RHP (under Other documents) a technical note is published with more information and an instruction on how to send samples and how much for this specific research project into residues in raw materials.
The growing media sector increasingly uses renewable raw materials and residual flows. These raw materials may contain residues as a result of (culture) activities. In the coming years, RHP wants to draw up a clear framework for the assessment and communication of residues. A distinction is made here between the different groups of chemical agents: insecticides, biocides and fungicides on the one hand and herbicides and growth regulators on the other.
In recent years no (culture) problems have been experienced with residues of insecticides, biocides and fungicides in the levels as found. But these substances can be taken up by plants and possibly cause levels that exceed the MRL (Maximum Residue Limit) for consumption crops. RHP wants to determine with the affiliated, certified companies which residues occur in substrate raw materials and substrate additions and test to what extent these are taken up again by crops. Based on this, MRL values for substrate raw materials can also be drawn up.
The harmfulness of a herbicide depends on the type of residue, the amount present and the sensitivity of the plant. Together with the affiliated, certified companies, RHP wants to gain insight into the possible effects of herbicides on germination and growth, with the aim of establishing damage thresholds in growing media. For the latter, targeted research using so-called “spiking” will also be carried out. An active substance is added to a substrate in an increasing concentration, whereby the plant response and uptake is recorded.
