On Monday 9 December, the members of two advisory groups gathered in Agrotopia. During the first meeting, as part of the VLAIO-LA InPaKt trajectory, they discussed the progress in controlling CGMMV. The second meeting focused on the CABY virus. In between, the attendees visited the fruit and vegetable greenhouses, where they explained the trials with illuminated cucumbers. 
Monitoring drain water can predict cucumber mottle outbreak
Cucumber mottle virus (CGMMV) remains one of the biggest challenges for the Flemish cucumber sector. Many companies were also affected in 2024 (at least 27% according to a recent survey). Although some already noticed symptoms in February, we can say that 2024 was quieter than 2023.
The consortium shared a lot of test results. The virus spreads mainly through mechanical transmission. It can also be transmitted through water, but that is slower. Nevertheless, monitoring the water is very valuable. Matthias Laureys (Scientia Terrae) shared the insights from the drainage water monitoring campaign.
- By monitoring drainage water every two weeks using quantitative PCR (qPCR) and Near Full Genome analysis (NFG-PCR), an image can be formed of the virus pressure present on a cucumber farm.
- In addition, drain monitoring can be seen as a warning tool. In one example, the virus was already detected in the water 11 weeks before symptoms were visible in the plants
- These techniques also make it clear that some growers can still optimize their water disinfection.
Critically evaluating race sensitivity
Jari Van Dam (PSKW) once again repeated the most important infiltration routes and how you as a grower can take action against this.
- A good (winter) cleaning is important, with a logical plan of action as the main priority
- Removing diseased plants is also a way to slow the spread
- Disinfection of all incoming material prevents contamination
- Provide a hygiene lock or at least a disinfection mat at the entrance to the cultivation zone
In addition, the pot tests with numerous varieties were analyzed.
- Most varieties labeled as 'intermediate or highly resistant' by breeders actually show fewer leaf symptoms. However, virus multiplication still occurs in these varieties, so 'tolerant' or 'less susceptible' would be better descriptions.
- The results of the field trials carried out are in line with those of the pot trials in the sense that varieties that are more sensitive often also produce less and show more severe symptoms when attacked by the virus.
Symptom database and brochure should help displace CABYV
Another threat is the CABY virus, a virus that is spread very quickly by cotton aphids. In 2024, most cucumber growers were fortunately spared from CABYV. Erik van Vliet, advisor at Delphy, shed light on the situation in the Netherlands, where a major outbreak did rage in the Westland region. The presence of infected aphids seems to be the only trigger for an outbreak for the time being. If you can keep the aphids out of your crop (also on new planting material) or if there is no CABYV in the vicinity, there is a good chance that you will be spared.
- The project delivered a symptom database comparing different causes of chlorosis: Symptom database
- A brochure with tips and tricks for checking this virus has also been created:
Information brochure
Tour of Agrotopia
Many visitors were visiting Agrotopia for the first time, which naturally called for a tour. After a short introduction at the Stadstuinbouwplein, researcher Simon Craeye took them along the two vertical farming installations:
- a fully closed VF, where preparations are being made for strawberry cultivation
- and a hybrid system in the 12-metre-high façade greenhouse, where different types of lettuce enjoy a combination of artificial and natural light in a rotating system.
The tour continued along the illuminated cucumber greenhouses, where research and demonstrations take place within the VLAIO projects Led FR, OptiWAIE and ZERO-WASTE. The growers were able to determine
- that far-red light ensures beautiful leaf stem elongation,
- that the use of alternative water requires attention to correct fertilization
- and that the use of alternative tying systems or foil-free mats can ensure less waste without insurmountable challenges in terms of crop control.
Of course, all of this was done in accordance with the applicable hygiene protocol (avoiding sneaking in, remember?): everyone went through the hygiene lock, wore a full hygiene suit and disinfected their gloves with Virkon.
Source: Inagro