Using ADEM to manage powdery mildew (Apple powdery mildew)

ADEM is a PC-based system which gives warnings of several apple diseases, including models of apple scab, apple powdery mildew (PODEM), apple canker and fruit rot and fireblight.

  • The models are driven by weather variables including rainfall, surface wetness duration, ambient temperature and ambient relative humidity.
  • These are recorded by a data logger or weather station sited in the orchard or at a convenient site on the farm, and downloaded to the PC either directly or via a laptop computer.
  • The mildew model forecasts the epidemic of secondary mildew by combining the effects of weather on spore production and dispersal, infection and subsequent colony development on young leaves, with varietal susceptibility and the amount of mildew inoculum recorded in the orchard.
  • The index of mildew risk generated can then be used to assist in decision-making on fungicide use.

Assessments of primary and secondary mildew should be made.  These are classified as low, moderate or high and then put into the ADEM model running on the PC, along with varietal susceptibility and weather data.

  • The mildew risk generated is predictive as it forecasts the amount of mildew in the orchard which is likely to be sporing in 3-4 days time.
  • Using this information, decisions on fungicide use are made in the same ways as if based on mildew assessments only, but by using the mildew risk derived from ADEM, which gives information on the future progress of the epidemic, the decisions on fungicide use are more robust.