With oilseed rape (OSR) about to enter the critical flowering period in the UK, AHDB has restarted its sclerotinia infection risk alerts service for 2019.
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The web-based service uses a simple traffic-light system to highlight the UK areas where weather conditions are currently, or are forecast to be, suitable for the sclerotinia pathogen to infect crops.
Covering other key infection information, such as spore pressure data, the service can help focus monitoring efforts and guide the application of protectant fungicides.
Each spring, warm (>10°C), moist soils bring an end to Sclerotinia sclerotiorum’s overwintering stage in the soil, with the development of brown spore-releasing structures. Carried in the wind, the spores can land on OSR, feed on petals and germinate.
Even where spores are present and food is sufficient, conducive weather is still required for infection to occur. OSR is at the greatest risk of infection when relative humidity is greater than 80% and air temperatures are at, or above, 7°C for more than 23 hours.
The infection risk alert service uses observed daily weather data, from the Met Office and Agrii, and forecast data, from Iteris ClearAg, to highlight infection risk for the last 24 (observed) and next (forecast) 72 hours.
For the first time, the service is powered by the AHDB WeatherHub, which means many more sites can be included in the alerts. A traffic-light system is used to mark each UK site as either:
Green = no infection risk alerts forecast
Amber = conditions forecast to come close to triggering infection risk alerts
Red = infection risk alerts forecast
Available for each site, charts show an hour-by-hour breakdown of the observed and forecast sclerotinia infection risk. The observed data in the chart highlights whether any infection risk periods have already occurred.
Commentary, written by ADAS pathologists, is also published as part of the service. This highlights any regional infection risk alerts and near misses, alongside information on crop growth stage. With co-funding and support from BASF, it also provides information on sclerotinia inoculum pressure, based on weekly spore trap (six sites) and petal test data. ■