Spider mites Spider mites are already active on some outdoor crops so map out a strategy of chemical rotation for spider mite control to avoid resistance. Protected crops have a choice of Borneo (2008-1216), Dynamec, Gyro, Hallmark WZT (2008-2944), Masai, Majestik, SB Plant Invigorator and Sequel (2007-0902). Majestik and SB Plant Invigorator are fully compatible with biological control once they have dried on the plant. IPM spider mite programmes should also be started now. Make sure you have plant-to-plant foliage touching for good predator dispersal. The use of white fleece over non-touching plants can provide a useful predator pathway.
Powdery mildew Research work carried out on Azalea powdery mildew showed that it can develop at much lower temperatures than other mildew species. Check on deciduous Azalea foliage as it emerges for signs of the white growth. Start a spray programme using contact products such as Nimrod or potassium bicarbonate and use a protectant product seven days later. Check the foliage of miniature roses too. Products also available include Amistar (2009-0443), Bumper 250EC (2009-0707), Stroby WG, Systhane 20EW for protected crops and Cyflamid (2007-0512) or Folicur for extended control on outdoor crops.
Western flower thrip larva on foliage As soon as the air temperature starts to rise we can expect the activity of western flower thrip larva on foliage to become more obvious. The tell-tale scratching of the foliage can quickly ruin a perfect plant ready for dispatch. Control with Conserve or predators as soon as seen.
Leaf hopper on foliage The other pest that can cause leaf surface scratching is leaf hopper. These small and very frisky pests tend to be seen on sage, Lamium, Chrysanthemum and bedding plants. Control with applications of systemic products such as Chess WG (2008-2834) or Intercept 70WG, or contact products like Decis, Stalwart and Toppel 100 EC (non-IPM) or Majestik. Systemic granular products incorporated into compost also have some effect.
Blossom/bud wilt Check for dead buds on Malus and spray with Cercobin WG (2008-1384) to control Botrytis infections of opening buds.
Growth regulators The second application of growth regulator should be applied now on nursery stock. Low-dose and repeated applications work far more effectively on shrub subjects.