Lavenders: Maintain shab and Botrytis controls particularly in damp or humid conditions with Octave, Serenade ASO (EAMUs required), Signum (EAMU 2012-2141) or Switch. Ensure good airflow around crops.
Buddleja: Black sticky spots on leaves and stems called "guttation" on protected Buddleja, Digitalis or Phygelius is a natural plant response to differences in day and night temperatures. There is no damage to the leaf and irrigation or hand watering will remove it over a couple of days.
Dahlia smut: Pale spots usually occur first on the lower leaves during cool, wet conditions. Space crops, improve air circulation and light penetration and reduce leaf wetness periods. Control with Amistar (EAMU 2009-0443), Bumper 250EC (EAMU 2014-1274), Signum (EAMU 2012-2141) or Systhane 20EW.
Astrantia: Control leaf spotting with broad-spectrum fungicides such as Amistar (EAMU 2009- 0443), Bumper 250EC (EAMU 2014-1274), Signum (EAMU 2012-2141) or Switch.
Whitefly: Control on non-edible crops using Calypso (EAMUs required), Chess WG (EAMU 2013-2016), Decis, Gazelle SG, Hallmark WZT (EAMU 2008- 2944), Mainman (EAMU 2013-0045), Majestik, Mycotal, Movento (EAMU 2011-1987), Naturalis-L, Pyrethrum 5EC, Savona, SB Plant Invigorator, Spruzit or Toppel 100 (EAMU 2013-2410).
Biocontrol: Increase predator numbers week-on-week. Warm weather will require a switch to more tolerant species such as Amblyseius andersoni or A. californicus for spider mite control.
Fireblight: This is a notifiable disease. Remove all suspect plant material and burn it - do not compost or recycle. Removing flower trusses of Crataegus and other vulnerable plants to help reduce the risk of infection.
Leaf spots: Maintain leaf spot controls on Helleborus, pansies, phormium and yucca. Products available include Amistar (EAMU 2009-0443), Bravo 500 (EAMU 2010-1130), Rovral WG (EAMU 2011-3200), Octave, Serenade ASO (EAMUs required), Signum (EAMU 2012-2141) and Switch.
John Adlam, Managing director, Dove Associates