Weed control: Control perennial weeds on previously uncropped land before planting.
Thistles, docks and creeping nettle can be difficult to eradicate post-planting. Glyphosate or Dow Shield on weed foliage is usually effective. Volunteer cereals and couch can be controlled later by Laser, Falcon or Panarex (SOLA 2006-0364).
Downy mildew: Check buddleja, digitalis, geum, hebe, osteospermum, pansy, roses and other susceptible herbaceous perennials as temperatures increase. Use products such as Aliette 80WG, Fubol Gold WG (SOLA 2010-0567), Filex/Proplant, Invader (SOLA 2011-0717), Signum (SOLA 2009-1842) or Subdue plus a wetting agent.
Caterpillars: Keep a look out for tortrix moth caterpillars - they cause leaf rolling and crop disfiguring. For IPM-friendly systems, apply Conserve, Nemolt (SOLA 2010-2131) or Majestik, otherwise use Toppel 100EC or Decis.
Spider mites: It is not too late to apply Apollo 50SC on outdoor acer, Malus, prunus and Pyrus to control over-wintering spider mite eggs. Treating plants now helps to get on top of problems early. A SOLA is required for use under protection.
Compost tea: Clean out equipment thoroughly to start the fortnightly applications as new foliage emerges. The beneficial micro-organisms compete for space on the foliage and in the root zone, which can reduce the risk of disease pathogens establishing on crops. The brew has numerous other benefits too.
Frost and spraying: Avoid spraying when frost is around and only spray when there is no risk of frost at night. Many products have adjuvants in them that enhance uptake or increase efficacy but can leave young foliage without adequate cuticle and vulnerable to quite mild frosts.
Lupins: The seed-borne disease Colletotrichum produces tell-tale spiralling of foliage with darkened and fallen stems. Control as soon as seen with Scotts Octave or Switch.
Sciarid fly: Larvae are starting to become an increasing problem, particularly at the propagation and liner stage. In small areas, consider drenching with nematodes (Steinernema feltiae) or introduce Hypoaspis or Macrocheles mites. Larger areas and bigger infestations can be treated with the rove beetle Atheta coriaria - introduce breeding colonies using HDC HNS fact sheet 06/10.