Plants may not show any symptoms until they start to put on new growth, which could be as late as April. Look at roots of random plants in a batch during the despatch period to avoid customer complaint.
Gleditsia pea gall - The timing of pesticide applications is the key to successful control of this disfiguring pest. Spray the emerging leaflets using products such as Admire, Gazelle, Hallmark WZT (SOLA 2008-2944) or Talstar 80 Flo. Applications of Certis Spraying Oil in the autumn will control over-wintering egg populations.
Powdery mildew - Check deciduous Azalea foliage as it emerges from now on for the first signs of the white mycelial growth - it can develop at much lower temperatures compared to other powdery mildew species. Start a spray programme using contact products such as Nimrod or potassium bicarbonate, followed by a protectant product seven days later. Avoid spraying if frosts are predicted. Miniature roses are often the first to show mildew symptoms, so check their foliage too.
Choisya - I find many growers struggle with stem and root rotting on this genus. In many cases it can be identified as a fungal infection such as Pythium. I do think, however, that timing along with good growing media and water management have big parts to play in successful Choisya production. Potting them earlier, between February and April and watering with care, seems to allow better root establishment and a stronger plant that resists root fungal attacks. This has now been borne out by the recent Horticultural Development Company project 169.
Anemone - Control leaf and stem nematode with Vydate 10G (SOLA 1993-0020). Read the label and SOLA carefully before application. Some growers have had phytotoxicity with certain plant species.
Propagation - Early shooting of growth means that cutting material of protected herbaceous and shrubs will need to be either utilised or cut off and allowed to break again rather than let it get too long and leggy.
Rust mites - If seen, apply Dursban WG, Hallmark WZT (SOLA 2008-2944), Envidor (SOLA 2009-3366) or Dimilin Flo to ash. Use a hand lens to inspect stems - they are small white mites barely visible with the naked eye. Include Poplar, Tilia and willow that may have had gall mite damage last season.
- John Adlam is managing director at Dove Associates www.HorticultureWeek.co.uk/nursery for recent articles.