Leaf hopper: These small and very frisky pests tend to be seen on ornamental sage, Lamium, Chrysanthemum and bedding plants. Control by applications of systemic products such as Chess WG (SOLA 2008-2834), imidacloprid in the growing media or contact products such as SB Plant Invigorator or Majestik. Also available are Decis or Toppel 100EC (both non-integrated pest management).
Sawfly: Watch for small, green caterpillars of the Aquilegia sawfly that can cause widespread defoliation. If you see any foliage damage, spray outdoor crops with Toppel 100EC or indoor crops with Nemolt (SOLA 2007-2120) immediately. A delay of two days can be too late.
Bacteria: Apply Croptex Fungex after wet periods to control bacterial leaf spots on Begonia, Hedera, Prunus, Mahonia and stocks. Turn off overhead irrigation for 24 hours after spraying to give the product time to work. Include Serenade ASO (SOLA 2009-0246), which can be tank-mixed with copper fungicides, in your control programme.
Craneflies: Adult activity of craneflies suggests that leatherjackets may be present in the next few weeks. Liners and small pots are at most risk with damage to the base of the plant at ground level. Products containing chlorpyrifos and pellets containing methiocarb have approval for this task. Always check the product label to see whether you can use it under protection because some of these products can only be used outside. Also available are nematodes for drenching into pots.
Soil sterilisation: Soil temperature is warm enough for Basamid applications. Soil must be deeply cultivated and fine to get good control of weeds, seeds, pests and diseases. A polythene covering will increase the vapour intensity. Leave it on until the last possible moment and the soil will remain clean of weeds for longer.
Scale: Control pests with Decis, Chess WG (2008-2834) or Savona.
Sciarid fly: Warmer weather means sciarid fly larvae start to become an increasing problem. To keep larvae at low levels in small areas, consider drenching with nematodes or introduce Hypoaspis. Larger areas and bigger infestations can be treated with the rove beetle Atheta coriaria. Horticultural Development Company work has shown the many benefits of maintaining a population of these predators in glasshouses.
Box blight: Nurseries can control this with sprays of Cercobin WG (SOLA 2008-1384) plus Bravo 500, Switch or Signum (SOLA 2009-1842).
- John Adlam is managing director at Dove Associates www.HorticultureWeek.co.uk/nursery for recent articles.