Only a consistent spray programme will control these persistent pests. Include an adjuvant in your spray tank, where appropriate, to increase spray effectiveness and enable better penetration of the "wool". Products such as SB Plant Invigorator and Majestik provide good contact-acting control.
Powdery mildew Spray Amistar (EAMU 2009-0443), AQ10 (EAMUs required), Bumper 250EC (EAMUs required), Corbel (not on roses), Folicur, Kindred, food-grade potassium bicarbonate, Nimrod, Signum (EAMU 2012-2141), Stroby WG, Reflect (2016-1602) or Takumi SC (EAMU 2013-1294) depending on crop location and predator use.
Compost tea Valuable disease suppression can be achieved, particularly on protected crops. Fargro, Martin Lishman, Symbio and XL Horticulture sell brewing systems.
Thrips Control scratching/flecking damage on foliage and flowers with Conserve, Dynamec or Naturalis-L. Use Amblyseius andersoni, A. cucumeris, A. montdorensis and A. swirskii mites or Orius spp. for adults/larvae. For pest pupae, use Macrocheles robustulus mites, Gaeolaelaps aculeifer or Stratiolaelaps scimitus. Steinernema feltiae parasitic nematodes can be applied to foliage, soils and growing media depending on pest life stage. Alternatively, control using Conserve, Decis (EAMU 2014-1011), Dynamec, Hallmark WZT (EAMU 2008-2944), Majestik, Naturalis-L, Pyrethrum 5EC, SB Plant Invigorator, Spruzit or Toppel 100 depending on location and predator use.
Herbicide applications Keep up-to-date on field-grown crops and newly potted stock once compost has settled. Most herbicides are poor at controlling emerged weed seedlings.
Mulches Where possible, consider applying bark mulch to compost surfaces, ensuring good coverage to retain moisture and prevent weed infestation.
Leaf miners Control leaf damage on protected, non-edible crops using Dacnusa and Diglyphus wasps alongside short-term effect products such as Dynamec or Movento (EAMU 2011-1987). Non-IPM products include Hallmark WZT (EAMU 2008-2944). Selected pheromone traps are also available for timely predator or pesticide applications.
Leaf spots Protect foliage using Amistar (EAMU 2009-0443), Bravo 500 (outdoor crops, EAMU 2011-1130), Rovral WG (EAMU 2018-0241) or Switch on hellebores, pansies, yucca, ceanothus and viburnum.
JOHN ADLAM Managing director, Dove Associates