Two-spotted spider mite (TSM) - Apply Apollo 50SC on all vulnerable crops to prevent eggs from developing any further - you can gain maximum effect by applying when the eggs start to change colour from red to orange. Target outdoor crops of Acer, Malus, Prunus and Pyrus and use SOLA 2001-2271 for application over protected crops. You should order predators now if TSM is active on protected crops. When plants are first potted and foliage is not touching, they cannot pass from plant to plant. Make sure, therefore, that predator distribution is widespread at this time of year. You can lay white fleece on the foliage as a bridge during early growth stages. Map out a strategy of chemical rotation to avoid TSM resistance. Protected crops have a choice of Apollo 50SC (SOLA 2001-2271), Borneo (SOLA 2008-1216), Dynamec, Majestik, Oberon (SOLA 2004-1718), SB Plant Invigorator, Sequel (SOLA 2009-3061) and Talstar 80 Flo. Check the labels for biological control compatibility.
Weed control - If you are planting out material on previously uncropped land, make sure that perennial weeds are controlled first. Patches of thistle, docks and creeping nettle can be difficult to eradicate once the crop is in situ. Glyphosate or Dow Shield is usually effective. Volunteer cereals and couch can be controlled later by applications of either Laser or Falcon over the crop. Consider the use of Betanal Flow (SOLA 2008-2824) to control seedling weeds that can emerge after herbicide applications. The application rate is dependent on the air temperature at the time of application. Avoid spraying if a frost is forecast the night after application or you may get crop damage.
Bark beetles - Control emerging adults by spraying the stems of pines and ornamental cherries with Dursban WG.
Rust - This disease is expected any time now on Fuchsia, hollyhock and Mahonia. Check the stems and backs of new leaves and spray with Amistar (SOLA 2009-0443), Bumper 250EC (SOLA 2009-0707), Signum (SOLA 2009-1842) or Systhane 20EW.
John Adlam is managing director at Dove Associates www.HorticultureWeek.co.uk/nursery for recent articles