Disinfection of Recirculating Water of Strawberry Tray Fields (RECUPA)

Horticulture Belgium
Until recently, the water used in the cultivation of strawberry cuttings was largely discharged into the surface water via single discharge points. Not only did this result in a great loss of water, but also of nutrients and plant protection products. Several disinfection techniques were tested.

The challenge

To guarantee strawberry production, the young plant material must be grown free of pathogens, therefore closing the water flow of tray fields is not without its challenges. Consequently it is crucial that the drainage water coming from the tray fields is disinfected to prevent plant pathogens, such as Verticillum spp, Phytophthora spp, Pythium spp.,…. During the course of this project, Huwa-San TR-50 was tested as a disinfection technique to disinfect the collected waste water.

proefopstelling_Figuur1_trayfield_strawberry
Figure 1: Schematic representation of trial method.

Trial design

To test and compare different disinfection techniques, 3 pilot installations were built at the Research Centre Hoogstraten (PCH). The water from the tray fields was collected in a preliminary pit and then pumped into the dirty drain.

For the technique with Huwa-San TR-50, a pre-filtration system was installed after the dirty drain. The vibrating screen and the cloth filter delete any organic pollution present in the collected water. The filtered water enters the clean drain where Huwa-San TR-50 is administered via a pulse pump. Huwa-San TR-50 has a disinfecting effect on the clean drain, so that the water is ready to be used again during the next watering round (Figure 1).

Results

Over a period of 17 weeks, samples were taken at fixed intervals from both the dirty and clean drains. The presence of pathogenic fungi was tested through plating and also through DNA multiscans. To determine the efficiency of the different techniques, these results were compared to those of the slow sand filter already present at the PCH. The slow sand filter served as a reference standard.

The results of plating for the slow sand filter show a clear difference in colony forming units per millilitre (cfu/ml) between the dirty drain (grey bar) and clean drain (green bar). Statistical models show a significant reduction (asterisk + brackets). All disinfection techniques tested showed a significant reduction, with Huwa-San TR-50 showing the greatest reduction.

Figure 2a: Comparison of results of fungal plating between dirty and clean drains of the different disinfection techniques. Where brackets + asterisk show significant difference between dirty and clean drains
Figure 2b: Comparison of infection rates based on DNA multiscans between dirty and clean drains from the different disinfection techniques. Again, the brackets and asterisk indicate a significant difference.

The dirty drain started with an average of 1700 cfu/ml, which was reduced to <100 cfu/ml (see Figure 2a). The DNA multiscans also confirmed the disinfecting effect of Huwa-San TR-50, here too a significant and strong reduction in the level of infection was established (see Figure 2b).

Finally, a crop and phytophthora assessment was carried out (figure 3). The crop assessment confirmed healthy plant material, with the cuttings rooting well and without phytotoxic damage. Furthermore, 9 out of 10 cut rhizomes showed no brown discolouration, and these were visually free of Phytophthora spp.

Figure 3a
Figure 3b
Figure 3c
Figure 3d

Figure 3a – 3b – 3c – 3d: Photographs of the plant material and rhizomes during the crop and Phytophthora spp. assessment.

Data generated in the framework of the Recupa project financed by the ERDF under the Interreg Flanders-Netherlands programme.

Conclusion

The test demonstrated that Huwa-San TR-50, in combination with pre-filtration, produced an effective result in eliminating fungal pathogens, which means that Huwa-San TR-50 significantly reduces fungal pathogens. This is confirmed by both the plating and the DNA multiscans. The young plant material was also found to be healthy at the end of the propagation.

  • Recyclable water
  • Leaves no odour and no colour
  • Prevents the spread of pathogens
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Huwa-San TR-50 is a registered biocide. Use biocides safely. Before use, read the label and product information.

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