Hot, sunny weather Avoid spraying in the middle of the day. Only spray products that are emulsifiable concentrates during the cooler times of the day to avoid foliage scorch. This can also be said for watering. Make sure that your abstractions do not exceed the daily levels of your licence.
Plant sap Hot weather can cause allergic skin reactions to sap on some staff. Euphorbia and Ruta are particularly noted for causing skin blisters when sap and ultraviolet combine together. Remind staff of this and, as part of your health and safety policy, mark those plants with a recognisable symbol to help staff who speak little English.
Herbicides Chikara can be tank-mixed with glyphosate to control a wide range of perennial weeds. It is safe to apply around the base of a number of established tree species but it will not control hairy bittercress or field horsetail. Skirmish is a soiland foliar-acting field herbicide with up to eight weeks' control on emerging weed seedlings. It can be tank mixed with products such as Roundup Biactive or Stomp 400SC (SOLA 2008-2923).
Irrigation pipes Remind staff of the dangers of moving irrigation pipes in fields with power lines overhead. Irrigators should also be set so that they do not spray onto power lines.
Sawfly Read the new Horticultural Development Company (HDC) fact sheet (11/10) on turnip sawfly, which can attack some green manure crops. Control products include Decis, Hallmark WZT or Tracer.
Pearlwort HDC work has shown that a number of herbicides will control this weed. These include Flexidor 125 (protected SOLAs required) if applied as a pre-emergence during the growing season. Butisan-S, Chikara, Skirmish and Sumimax (SOLA 2008-2881) work well as winter applications. Skirmish also showed good post-emergence control. Research suggests that a coarse pot surface makes it less likely for pearlwort to germinate. If this weed is a problem, consider using a coarse peat growing media or bark top mulch.
Eucalyptus Keeping eucalyptus shaded during the hot, sunny times will avoid the bumpy leaves on the tops of the plant. This is not a disease but oedema caused by high temperatures and high humidity. Try to keep these plants in a shaded area and do not over-water them. It will have no effect on the plant and growth will be quite normal.
John Adlam is managing director at Dove Associates www.HorticultureWeek.co.uk/nursery for recent articles