At the end of last year, members of two guidance groups gathered in Agrotopia. At the first meeting, framed within the VLAIO-LA trajectory InPaKt, they discussed progress in the control of CGMMV. The second meeting focused on CABY virus. In between, attendees visited the fruiting vegetable greenhouses, where they explained trials with exposed cucumbers.
Monitoring drain water can predict cucumber fur outbreak
Cucumber fur virus (CGMMV) remains one of the biggest challenges of the Flemish cucumber sector. A lot of farms were also affected in 2024 (at least 27% according to a recent survey). Although some noticed symptoms back in February, it is fair to say that 2024 was calmer than 2023.
The consortium shared a lot of trial results. Spread of the virus is mainly via mechanical transmission. Via water is also possible, but it is slower. Still, water monitoring is very valuable. Matthias Laureys (Scientia Terrae) shared insights from the drain water monitoring campaign.
By monitoring drain water biweekly via quantitative PCR (qPCR) and Near Full Genome analysis (NFG-PCR), a picture 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 seen in the plants
These techniques also highlight that some growers can still optimize their water disinfection.
Variety sensitivity to be critically evaluated
Jari Van Dam (PSKW) reiterated the main routes of incursion and how growers can combat them. A good (winter) cleaning is important with a logical plan of action, removing diseased plants is also a way to slow down the spread, and disinfection of all incoming material prevents contamination. In addition, pot trials were dissected with numerous varieties.
Most varieties labeled 'intermediate or highly resistant' by breeders effectively show fewer leaf symptoms. However, virus multiplication still takes place in those varieties, so "tolerant" or "less susceptible" would be better descriptions.
The results of the field trials conducted are nicely in line with those of the pot trials in that varieties that are more susceptible also tend to produce less and show more severe symptoms when affected by the virus.
Symptom database and brochure should help repress CABYV
Another threat is the CABY virus, a virus spread very rapidly by cotton aphids. In 2024, most cucumber growers were fortunately spared from CABYV. Erik van Vliet, consultant at Delphy, shed light on the situation in the Netherlands, where a severe outbreak did rage in region Westland. For now, the presence of infected aphids seems to be the only trigger for an outbreak. If you can keep the aphids out of your crop (including on new planting material) or if there is no CABYV around, chances are you will be spared.
The project delivered a symptom database comparing different causes of chlorosis: Symptom database
A brochure with tips and tricks for controlling this virus was also produced:
Infobrochure
Tour of Agrotopia
Many visitors visited Agrotopia for the first time, which naturally called for a tour. After a brief introduction at the Stadstuinbouwplein, researcher Simon Craeye took them around the two vertical farming installations:
a fully enclosed VF, where preparations are being made for a strawberry crop
and a hybrid system in the 12-metre-high gable greenhouse, where different types of lettuce in a rotating system enjoy a combination of artificial and natural light.
It also passed by the illuminated cucumber greenhouses, where research and demos take place within the VLAIO projects Led FR, OptiWAIE, and ZERO-WASTE. The growers were able to observe that far-red light ensures nice leaf stem elongation, that the use of alternative water requires attention to correct fertilization, and that the use of alternative tying systems or foil-less mats can ensure less waste without insurmountable challenges to crop management.
Of course, all this was done according to the hygiene protocol in force (avoid sneaking in, remember?): everyone passed the hygiene lock, wore a full hygiene suit, and disinfected hand shoes with Virkon.
Source: Inagro