By Sakeena Rajpal, GLOBUS Communications and Events Officer

As the air turns crisper and colder, and the festive season draws closer and closer, I suddenly remembered how important roast vegetables are to a perfect Christmas dinner, shining like jewels as they arrive crispy and tender out of the oven on Christmas day. This is not forgetting how important vegetables are in a perfect Sunday roast, or even in a hearty vegetable soup after a long, tiring, cold day of work…

As I continued to reminisce about food, this led me back to remember the ‘Quarantine Field’ at the Warwick Crop Centre– a unique facility in the UK that plays a significant role in sustainable crop disease management . The research at this facility led by Professor John Clarkson focuses on combatting soil-borne disease caused by pathogens. This restricted access area is a ground for trialling new crop protection products and assessing new crop varieties for disease resistance, through diagnostics and biological control.

So why are these pathogens so dangerous? These pathogens (mainly fungal) can reside in soil for years, and even up to decades making soil borne diseases difficult to control. Some of the key soil-borne diseases that are being focused on are :

• Fusarium wilt (caused by the fungal pathogen Fusarium oxysporum), which is commonly found in onion, peas and cabbage. What makes this fungal pathogen difficult to treat is that they have evolved to uniquely infect a variety of plants. Additionally, through staying in plant debris they manage to infect plants even when changing crop cycles. The roots of these vegetables can be infected with Fusarium oxysporum, interfering with their vascular system, decreasing water and nutrient uptake. The main signs of infection include wilting as well as ‘faded, yellow, foilage’. Despite it being able to be treated with soil fungicides, many Fusarium oxysporum forms are able to develop resistance. Research within this area includes genome sequencing to identify and locate genes linked to host specificity of F.oxysporum.

• Sclerotinia disease (which can be caused bySclerotinia sclerotiorum) . This disease can occur on carrot, lettuce, peas, beans and potatoes- and even wild flowers. This fungal pathogen also survives in soil, and can germinate to produce structures which release ascospores (sexual reproductive structures) of fungi into the air, infecting plants. Infection of Sclerotinia leads to rotting and death of the plant, and white mould on the surface of plant tissue is a common sign. Further research is being conducted into the biology of this fungal pathogen as well as into the environmental conditions that affect the lifecycle of S.sclerotiorum to develop ‘disease forecasting strategies’. Resistance of  S.sclerotiorum in lettuce and other vegetables also needs to be identified. Finally there is research into disease control using biofumigation– a method that involved applying a chemical (called glucosinolates) produced by plants, that when broken down supresses pests and microorganisms.

• Cavity spot of carrot (caused by the soilborne plant pathogen Pythium violae, an oomycete). Oomycetes are a class of microorganisms that pose as a large threat to food security worldwide. Signs of infection in P.violae include ‘small, pale and sunken’ spots appearing in what looks like an ‘intact outer skin’. As these spots expand and further infection occurs, the outer skin ruptures, causing open cavities. Whilst cavity spot of carrot can be controlled by the application of fungicides and potentially by long crop rotation between carrot crops, new approaches to control are needed. Like the other pathogens mentioned above, further research will be conducted in the molecular characterisation of P.violae as well as its interaction with other microorganisms and environmental factors. Additionally, biofumigation for the control of cavity spot is also being researched.

Overall, the ‘Quarantine Field’ (which is funded by the government and research councils such as the UKRI and the Agriculture and Horticulture Development Board) enables researchers such as John Clarkson and his team to collaborate with plant breeders and agronomists to sustainably improve our food systems. Through trialling crop varieties for commercial companies, successful yields of our all-important veggies are ensured, as well as the upkeep of UK farm’s livelihoods.  

Header image by Norbert via Pixabay