Case study 2 – Cavity spot on carrots

Cavity spot is a major disease of carrots which causes millions of pounds of damage in the UK each year.

The disease is mainly caused by an oomycete called Pythium violae, which attacks the mature carrot root causing small, black sunken lesions, which makes the carrots unmarketable. Currently, there is only one fungicide available for use against cavity spot, but growers are reporting that this is now working less than 50% of the time. Previous work has failed to find new control products due to large variability in response to inoculation with Pythium violae in field experiments.

Kathryn Hales worked on an AHDB-funded PhD studentship at Warwick University, using DNA-based methods to establish a more reliable way of identifying and tracking the pathogen in the soil over time. Her work involved developing an inoculation system to artificially induce cavity spot disease to allow for testing of new control products and was closely aligned with another project at Warwick where the inoculation was tested.

Ian Holmes, company agronomist at Strawsons

“Cavity Spot has long remained an enigma for carrot growers and is still the number one disease issue faced by the industry.  This work has made some notable progress in our basic understanding of cavity spot as a disease and will help us with approaches for control in the longer term.  The use of a reliable inoculation method is crucial in analysing and understanding if and how compounds available for test are able to affect cavity spot and is our best chance of finding suitable solutions, be they genetic, chemical or biological, to help growers manage the disease going forwards”.