Sciarid fly: As we enter the warmer months, sciarid fly larvae start to become an increasing problem, particularly at the propagation and liner stage so try to keep the larva at low levels to reduce damage on any newly emerging roots. In small areas, consider drenching with nematodes (Steinernema feltiae) or introduce Hypoaspis mites. Larger areas and bigger infestations can be treated with the rove beetle Atheta coriaria. HDC work (PC 239) has shown the many benefits of maintaining a population of these predators in glasshouses.
Growth regulators: The cost-effectiveness of spraying Bonzi, B-Nine SG or Dazide Enhance set against the cost of hand-trimming shrubs is very economical. The choice and rates of growth regulators can be daunting but talk to your adviser about the ones suitable for you. I favour repeated lower doses to the growing point rather than one heavy application.
Aphids: Populations of this pest are now increasing on new leaf tips and stems, so control programmes should be started. Herbaceous perennials, bedding and primulas seem to the most affected crops right now. Check your aphid species if you start to introduce predators to make sure you use the correct one or spray with IPM-friendly products such as Aphox, Chess WG (SOLA 2008-2834), Majestik, Savona or SB Plant Invigorator. Non-IPM products include Calypso (SOLAs required), Gazelle or Toppel 100EC. Avoid applying successive neonicitinoid products to keep the risk of resistance low.Remember to look at the product label to ensure compliance with any intervals between spraying and dispatch.
LED lighting: Research by the European Duncester Institute has shown that exposing plants to specific sequences of flashing LED lights after potting can affect weed germination. There was no need for herbicide applications because of the stop-start effect created by these flashes. Researchers believe it causes an initial disruption in germination which then stops weeds from further establishment in growing media.
Whitefly scale: Order Encarsia when you see the first signs of whitefly scale on the backs of leaves. Place the cards so they are not directly irrigated, with the parasitised black scales facing away from the sun.
Sticky traps: These should be distributed now to monitor the pests present on your crops.
Bark beetles: Bark beetles are emerging around this time. Spray the stems of pine and ornamental cherries with Dursban WG.