Fusarium 4 affecting crops in the UK
On the continent, indoor lettuce growers have been battling with Fusarium 4 (Fusarium oxysporum f.s.p Lactucae) over the last 3.5+years. Up to last week, this was contained to the Netherlands and Belgium. Unfortunately, Fusarium4 has now been identified in the UK, which could have severe consequences.
Fusarium4 is very aggressive without known treatment or breeding resistance to date. Soil sterilisation does not go deep enough and therefore has only a limited effect; cultivation will enhance spores from the subsoil. The optimum temperature for it is 24-28˚c, but it can also damage at 8˚c, and spores survive for a long time in soil and crop debris.
It's important that you're aware that the strain is now in the UK so that you can put measures in place to limit the spread and impact of the disease in your own crops and across the UK. Please look at the hygiene protocols you have in place for yourselves when working with lettuce and corn salad crops, and for visitors.
The pathogen can spread in the following ways:
- Crop debris
Control is extremely difficult, as there are no effective fungicides and soil sterilisation is limited in effectiveness.
Avoid spreading soil and crop debris by tractor, product and plant trays.
Sterilise boots, shoes, trays, pallets etc.
Visitors should wear overshoes and dispose of on site, not in vehicles and taken off-site with them.
Symptoms are yellowing, followed by necrosis of the lower leaves or wilting of the whole plant, but symptoms can also appear in young plants.
If Fusarium4 is suspected, most, if not all lettuce breeding companies will test for you, as will your local science organisation. If you have any suspicions, please have your crops tested to protect yourself and the industry.
Our inspectors are aware of this outbreak and will, where possible, avoid entering protected cropping areas where lettuce and corn salad are grown, ensuring that they use appropriate biosecurity measures, such as using disinfectant wash for boots, and wearing protective overboots and overalls when necessary.