The challenge: Cavity spot affects carrot crops across the UK, and can decimate harvests, with up to 10% crop losses each year, costing British farmers up to £30 million. Cavity spot (Pythium sp.) can be controlled with metalaxyl, but many reports have emerged showing that this treatment can sometimes show little or limited efficacy in many fields.
The study: FungiAlert worked with one of the UK’s largest agronomy companies to help understand more about the disease causing agents of cavity spot in carrot fields. SporSenZ sensors were deployed across fields known to be high risk for cavity spot. Where positive identification of Pythium was detected by the sensors, the nearby carrots were inspected for signs of cavity spot.
✔ The SporSenZ screen identified high populations of Pythium across all fields.
✔ Three different species of Pythium were found.
✔ All three species of Pythium detected had been previously associated with cavity spot.
✔ Correlation found between sensor location and visible cavity spot in carrots.
✔ The field had been sprayed with metalaxyl, however, interestingly, the species of Pythium found in the study were known to be less sensitive to metalaxyl-M based fungicides.
✔Metalaxyl is not able to reduce all populations of Pythium species associated with cavity spot. This means that in UK soils, concentrations of other cavity spot causing Pythiums are increasing each year. These emerging Pythium species are becoming more opportunistic, and it is likely that we will soon see higher incidences of cavity spot.
✔ FungiAlert’s SporSenZ screen has been instrumental in recognising the importance of different species of Pythiums as causing agents of cavity spot, and in discovering the build up in concentration of these species in UK soils.
✔ Importantly, this study has found a need to develop new disease management strategies to target new emerging Pythium species, which are known to be less sensitive to metalaxyl based products. This will ultimately lead to increased yields.
Future opportunities: Following this study, FungiAlert are currently working with growers and agronomy companies to understand the main cavity spot threats within their carrot fields, and to test the efficacy of other crop protection products/strategies for reducing the concentration of Pythium.