Adding a wetting agent to an eradicant spray application - check the fungicide label first - will help control stubborn powdery mildew. On ornamental trees, consider Corbel, Cyflamid (EoA 2007-0512) or Folicur, although warm days may cause foliar damage, especially with Corbel.
Check chrysanthemum, lamium, nepeta, lavender and salvia. Predator-friendly products include Chess WG (EoA 2008-2834) and Eradicoat. Broad-spectrum insecticides include Calypso (EoAs required), Decis, Gazelle SG or Hallmark WZT (EoA 2008-2944). Products with physical action - and a short-term effect on predators - that may also provide control include Pyrethrum 5EC, SB Plant Invigorator and Spruzit. For edible crops, check for label or EoA approvals and make sure that harvest intervals are completed before despatch. Systemic compost-incorporated products for non-edible crops such as Couraze, Exemptor and Imidasect 5GR will also have some effect. Yellow sticky traps can help with monitoring.
Recent wet weather has encouraged bacterial infections on a range of crops including magnolia, philadelphus and laurels. Spray with a tank mix of Serenade ASO (EoAs required) and Cuprokylt to reduce infection levels. Include Codacide Oil for longer-term adherence.
Sawfly Apply Decis, Toppel 100EC or Hallmark WZT (EoA 2008-2944) onto outdoor crops if pests are seen. They can be identified by their feeding - they bend their bodies into an "S" shape.
Chrysanthemum white rust
Watch for white, cream, brown or pink pustules that can be produced on leaf undersides along with yellow blotching. Keep leaves dry to reduce humidity. Control active disease with Amistar (EoA 2001-1684), Bumper 250EC (EoA 2009-0707) and other rust-control products.
John Adlam, Managing director, Dove Associates