Slugs: Expanding leaves of Hosta make a great meal for slugs. Ferramol Max is much safer to the environment and looks less unsightly compared to some of the other pellets. Decoy Wetex is a large pellet but remains effective even with overhead irrigation.
Shot-hole on Prunus: Wet weather increases the risk of bacterial infections on Begonia, Hedera, Mahonia and Prunus. Apply tank mixes of Croptex Fungex or Cuprokylt FL with Serenade ASO (SOLA 2009-0246) after the wet to control bacteria. Try to leave overhead irrigation off for 24 hours after spraying to give the product time to work. Add in a wetting agent to get good foliar adhesion.
Leaf hoppers: This pest causes leaf surface scratching and tend to be seen on Chrysanthemum, Lamium, Salvia and bedding plants. Control with systemic products such as Chess WG (2008-2834) or Intercept 70WG or contact products such as Decis or Toppel 100 EC (non-IPM) or Majestik. Systemic granular products incorporated into compost for non-edible crops such as Couraze, Exemptor and Imidasect 5GR will also have some effect.
Western flower thrip: Improving air temperatures means greater activity of thrip larva. The tell-tale scratching on the foliage along with frass can quickly ruin a perfect plant ready for despatch. Control with Conserve, Dynamec or predators before they cause growing point distortion.
Leaf spots: Wet, warm weather will encourage leaf spot pathogens to spread on Ceanothus, Clematis, Phormium, Viburnum and Yucca. Spray with Amistar (SOLA 2009-0443), Scotts Octave, Serenade ASO (SOLA 2009-0246) or Switch this month.
Scale: Nymphs are now emerging from under dead adult shells on citrus, Euonymus, ivy and yew. Control with Decis (non-IPM), Chess WG (SOLA 2008-2834), Intercept 70WG, Savona or SB Plant Invigorator if seen.
Broad mite and tarsonemid mite: These microscopic pests cause considerable damage in the form of stunting and distortion of buds on many ornamental crops including Aster, cyclamen and Fatsia. Dynamec, Majestik, Oberon (SOLA 2004-1718), SB Plant Invigorator or Sequel (SOLA required) are the best products to spray now, particularly if you have started an IPM programme for other pests.