Thielaviopsis (black root rot): Check for patchy black damage on roots plus black lesions at the base of stems alongside leaf yellowing. Drench with Cercobin WG (EAMUs required), Octave or Switch and prevent infections using Prestop (EAMUs required), Trianum P or Serenade ASO (EAMUs required).
Herbicide applications: Keep up to date on field-grown crops and newly potted stock once compost has settled. Weed germination is rapid right now and most herbicides are poor at controlling emerged seedlings.
Aphids: Apply Aphox, Chess WG (EAMU 2013-2016), Majestik, Movento (EAMU 2011-1987), Naturalis-L, Pyrethrum 5EC, Savona, SB Plant Invigorator or Spruzit. Non-IPM products include Calypso (EAMUs required), Decis (EAMU 2014-1011), Gazelle SG or Hallmark WZT (EAMU 2008-2944). See feature, p36.
Pythium and Phytophthora spp.: Avoid overwatering vulnerable plants including Chamaecyparis, Cytisus and Taxus. Control active infections using Fenomenal (EAMU 2013-1990) or Subdue. Repopulate composts with beneficial microorganisms using Prestop (EAMUs required), Serenade ASO (EAMUs required) or Trianum P.
Sawfly: Aquilegia, robinia, old rose stock, Tilia and others are susceptible. Check for small, green caterpillars that will quickly defoliate plants. Spray outdoor crops with Decis, Dimilin Flo or Tracer (EAMU 2008-2908).
Mulches: Apply bark mulch to compost surfaces, ensuring good coverage to retain moisture and prevent weed infestation. Coir mats, polythene slips, grit and shredded miscanthus are also available in varying quantities.
Scab: Check ornamental Malus, Chaenomeles, Crataegus and Pyracantha. Apply protectants such as Captan 80WDG (EAMU 2014-2510 - nursery fruit trees only), Karamate Dry Flo Neotec, Scala (EAMU 2011-1315), Systhane 20EW or Topas (EAMU 2015-2338 - protected nursery fruit trees only).
Feeding: Change to high-nitrogen liquid feed products on nursery stock using a 2:1:1 ratio on sprinkler systems and 2:0:1 on drip systems. Avoid applications on warm, sunny days to prevent unnecessary scorch. Add the second top dressing of nitrogen to tree crops according to your fertiliser programme but do not exceed 50kg/ha of N (150kg/ha ammonium nitrate).
John Adlam, Managing director, Dove Associates