Straight from our experts: residue studies in rotational crops

Raphaël DELMOTTE
Director of GLP studies for Staphyt France

Raphaël joined the Staphyt GLP team more than 20 years ago first as a technician and then as a senior manager. Since 2010, he has been in charge of the management of studies, i.e. the elaboration of the study plan, the follow-up of the different phases and the writing of the final report. He acts as a close link and guarantees optimal communication between the various participants and the sponsor.

What is the purpose of residue studies on a rotational crop? When are they required?

“The objective of these studies is to determine the amount of pesticide residues that could be accumulated, via soil uptake, in rotational crops grown under good agricultural practices. These data can then be used to establish crop rotation restrictions.

 Under EU Regulation 1107/2009 (283/2013), metabolism and magnitude of residues in rotational crops studies can be required. These studies are only required when there is a risk related to the persistence of the active substance or its metabolites in soil. In the case where significant levels of residues (> 0.01 mg/kg) are found in a laboratory study (metabolism study), a field study is required to determine in situ the residue levels.”

How are these studies conducted?

“We test fungicides, herbicides and insecticides. Two trials are usually required in Europe, one in the northern area and the other in the southern area. At least one of these two trials must be located on a sandy loam soil. The plots are usually irrigated to ensure optimal crop development.

With its 30 GLP-approved trial sites in Europe and its team of experienced technicians, Staphyt offers a wide range of locations.

Rotational studies are long and complex, with a minimum duration of two years. Soil characteristics (percentage of sand, silt, clay and organic matter, pH, moisture capacity) as well as a daily record of weather data and anomalies are monitored during the course of the study. A detailed knowledge of the history of crop and pesticide use on the selected plots is also crucial for this type of trial.

Once the site has been selected, the test proceeds as follows:

    • Application of the tested product generally on bare soil
    • Setting up of both control and treated modalities, using three representative crops, each planted at three different dates:

• A leafy vegetable (lettuce, spinach)
• A root vegetable (radish, carrot, turnip)
• A straw cereal

    • Spraying of the tested product at several frequencies:

• 1 month before planting
• 6 months before planting
• 1 year before planting

  • Residue sampling and analysis:

Soil sampling can be done when the product is applied to a depth of approximately 20 cm and then at planting or harvest to a depth of 30 cm.
All plant parts defined as edible, including root and tuber vegetable leaves, must be analyzed for residues that are relevant to the rotational crops.
Samples for residue analysis are sent to the analytical laboratory within 30 days after harvest (and must be kept frozen at -18°C before analysis).”

Why choose Staphyt to conduct rotational studies?

“Staphyt has over 30 years of experience in GLP study management. Today, the Safety Evaluation team is composed of about 100 technicians, study Directors and Principal Investigators based in 30 GLP-certified stations and 1 food processing laboratory.

This geographical network allows our customers to carry out multi-site studies in all agricultural production areas. Before launching the project, we study with the customer the feasibility of the rotational project and work on its optimization, especially for the most complex requests (crops, timing…) which require specific designs and which will therefore benefit from the expertise and network of Staphyt. 

At Staphyt, we also have a very efficient tool to communicate with our clients, the Phytnet extranet. The study managers can thus ensure project coordination and optimal communication with all the parties involved in the study.”

 For further information or to reserve your trial plots, do not hesitate to contact Célia Bastiani.