From the nursery

- Two-spotted spider mite: Mites are establishing on the new growth of Choisya, Crinodendron, Chrysanthemum, dahlias, Fuchsia, Hydrangea, Primula, roses, Sambucus and Viola.

Control with Phytoseiulus and in higher temperatures, Amblyseius californicus. Consider sprays of Borneo (SOLA 2008-1216), Dynamec, Eradicoat, Majestik, Masai (protected roses only), Naturalis-L, Oberon (SOLA 2004-1718), SB Plant Invigorator or Sequel (SOLA 2009-3061). For non-IPM systems, use up your bifenthrin (Talstar 80 Flo or Starion Flo) or consider Hallmark WZT.

- Whitefly: If you experience a lack of black scales on plants using Encarsia, then take a close look at what you do. Spraying one of the synthetic pyrethrins, even three months earlier, can destroy predator populations. Temperature can make all the difference. Place cards so they are not directly irrigated and ensure the black-scale side points north, away from direct sunlight. This will make all the difference to initial hatching. Consider introducing banker plants of Lavatera where a steady population of whitefly, Encarsia and Eretmocerus can exist, acting as a predator springboard to your crop.

- Nemolt: Although it is permitted to use this product until 31 January 2012, the manufacturers are no longer producing it.

- Wilt diseases: Plants of Aster, Hebe, Penstemon and Phlox can all suffer at this time of year. If you see sections of the plant wilting, or even a whole plant suddenly wilt during periods of high temperature, then this is the most likely cause. Spray these plants with Amistar (SOLA 2009-0443), Cercobin WG (SOLA 2008-1384), Scotts Octave, Signum (SOLA 2009-1842) or Switch to control the spread of either Fusarium or Verticillium wilt.

- Powdery mildew: Adding a wetting agent to an eradicant spray application can usually control stubborn powdery mildew on roses. Using products such as food-grade potassium bicarbonate or Nimrod with a wetter normally shifts those stubborn areas. On ornamental trees, you can use Corbel, but watch the warm days because it can cause foliar damage.

- Leaf miners: Pest levels continue to be high on fieldand container-grown crops. If seen, spray with Dynamec (IPM systems) or Decis.

- Spring flowering: Avoid trimming plants that you want to flower this autumn such as Viburnum tinus, Ilex and Callicarpa.

www.HorticultureWeek.co.uk/nursery for recent articles.


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