NL: Root knot nematodes can reach plants via water on ebb and flow floors

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The root-knot nematode Meloidogyne enterolobii can spread through ebb-and-flow water, as confirmed by research conducted by Wageningen University & Research (WUR). Contamination can occur when the water comes into contact with plants infected by these nematodes. Consequently, ebb-and-flow irrigation systems pose a risk for the spread of M. enterolobii. WUR conducted research on behalf of the NVWA into the transmission of these nematodes from infected plants to ebb-and-flow water, which initially interacts with plants and potting soil before being drained away.

Meloidogyne enterolobii, a tropical root-knot nematode not native to the Netherlands, has been consistently detected in imported batches of potted plants in recent years. This presents a risk of introducing infected plants into Dutch soil, with all its associated consequences. These minute organisms can cause significant (economic) damage to various crops, including tomatoes, peppers, cucumbers, and potatoes.

Research on Meloidogyne enterolobii nematodes in ebb-and-flow water
Previous studies had already shown that Meloidogyne nematodes could spread through irrigation water. It had also been demonstrated for various root parasites, such as M. incognita, that they could spread through ebb-and-flow systems. Therefore, spread in ebb-and-flow systems seemed possible for M. enterolobii as well. However, the extent to which this would occur remained uncertain.

Design and result of the study
WUR conducted a greenhouse trial with two host plants: tomato (Solanum lycopersicum cv. ‘Dometica’) and bonsais of the Japanese elm (Zelkova serrata). For the study, WUR used artificially infected tomato plants and Zelkova bonsais from an intercepted import batch.

The plants were placed in ebb-and-flow trays (one plant per tray), and over a period of eight weeks, an ebb-and-flow treatment (watering) was applied once a week. Subsequently, the ebb-and-flow water was collected and concentrated. WUR counted the number of M. enterolobii nematodes in this concentrated solution.

In the ebb-and-flow water from more than half of the tomato plants and all of the Zelkova bonsais with symptoms, M. enterolobii nematodes were found. This demonstrates that M. enterolobii nematodes can drain out of the pot in an ebb-and-flow irrigation system, thus contaminating the ebb-and-flow water.

Mandatory measures against root-knot nematodes
Since April 11, 2022, EU member states have been required to implement measures to prevent the introduction of these nematodes. Like other EU member states, the Netherlands must eradicate the organism if found to prevent further spread.

It is also crucial for entrepreneurs to take necessary measures to prevent contamination and spread. One can inquire about robust guarantees from the supplier. Moreover, it is important to physically separate the plants from other batches for at least ten weeks after import. Additionally, regularly checking the roots for nodule symptoms is advised. Ensure that the irrigation systems are kept separate and that water is effectively disinfected through methods such as heating, UV treatment, or ultrafiltration.

Maintaining detailed records is essential. Additionally, it is important to label the plants in a manner that allows for easy distinction between different batches. Finally, information on recognizing an infection with root-knot nematodes can be found here.

Source: NVWA

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