Bacterial infections Maintain sprays of copper and Serenade ASO (EAMUs required) on laurels, ornamental prunus, mahonia and magnolia.
Fireblight A notifiable disease. Remove all suspect plant material and burn it - do not compost or recycle. Trim Crataegus and other vulnerable plants (most infections occur on flower spikes).
Dahlias Watch for ring spot virus - distinctive with yellow spots with dark centres. It is spread by aphids.
Thuja Needle cast diseases cause browning of fronds. Spores spread in humid, damp conditions. Control with Bravo 500 (EAMU 2011-1130), Octave, Signum (EAMU 2012-2141) or Switch over the next few months.
Thielaviopsis Plants affected by black root rot will wilt and turn yellow. Roots show black tips or black patchy damage. Apply drenches of Cercobin WG (glasshouse crops only, EAMU 2011-1887), Octave or Switch to affected crops in their irrigation regime. Prevent infections using Prestop (EAMU 2012-0564), Revive P, Serenade ASO (EAMUs required) or Trianum P. Avoid long periods of wet compost.
Leaf spots Apply Amistar (EAMU 2009-0443), Bravo 500 (EAMU 2011-1130), Rovral WG (EAMU 2011-3200), Octave, Serenade ASO (EAMUs required), Signum (EAMU 2012-2141) or Switch to astrantia, Helleborus, pansies, phormium and Yucca.
Spraying Bees are attracted to honeydew. Avoid applying high-risk products until insects are not foraging. This can start early and finish late at this time of year. Advise local beekeepers of spraying activity.
Watering Check irrigation daily to avoid compost sitting wet. Encourage root production on poorly established plants using liquid feeds high in phosphate such as Everris Plant Starter, Solufeed 1:5:1, Universol Yellow or Hortimix 1:4:1. Use overhead irrigation later in the day to wash through salts that build up on plants grown on sand beds.
Escallonias Avoid yellowing of lower leaves by applying foliar sprays of Epsom salts (magnesium sulphate) applied at 15g per litre of water to run-off.
Astrantia Control leaf spotting that can occur in wet, humid conditions using Amistar (EAMU 2009-0443), Bumper 250EC (EAMU 2009-0707), Signum (EAMU 2012-2141) or Switch.
John Adlam, Managing director, Dove Associates