1 August - Airflow & nutrients

Botrytis - Maintain good airflow around crops with a lot of soft foliage, especially on changeable days. Vent as much as possible and treat using Prestop (EAMU 2015-2773), Signum (EAMU 2012-2141), Switch or Serenade ASO (EAMUs required). Protect crops using Rovral WG (EAMU 2011-3200) or Scala (EAMU 2011-1315).

Conductivity - Take weekly readings of liquid-feed stock solutions and composts to build up a picture of CRF nutrient release, using liquid feeding to maintain good levels of macroand micro-nutrients. Conductivity changes with temperature so take measurements at known water temperatures for consistency.

Spider mites - Borneo (EAMU 2008-1216), Masai, Dynamec and SB Plant Invigorator are useful products at this time of year. Use predators on vulnerable crops too, first checking pesticide compatibility. Naturalis-L will provide good knock-down control in tunnels and glasshouses with more than 60 per cent humidity.

Downy mildew - Control fungal growth using Amistar (EAMUs required), Fenomenal (EAMU 2013-1990), Fubol Gold WG (EAMU 2013-2288), Invader (EAMU 2012-0109), Paraat (EAMU 2011-2585), Pergado Uni (EAMU 2012-1605), Revus (EAMUs required), Signum (EAMU 2012-2141), Subdue or Valbon (EAMU 2014-2325).

Powdery mildew - Adding a wetting agent to mixes (check labels and not with emulsifiable concentrates) helps to extend control of persistent mildew, especially on roses and trees.

Pergado - Uni MAPP 15734 has an end-use date of 31 August 2017. The replacement MAPP 17513 currently has no onor off-label approvals for ornamentals.

Euphorbia - Avoid long periods of wet compost to prevent and control Phytophthora spp. infections that can spread rapidly through crops. Use Fenomenal, Subdue or Previcur Energy (EAMU 2011-1557) where infection has established. Plant Trust contains a slow-release formulation of fosetyl-aluminium; Prestop (EAMU 2015-2773), T34 Biocontrol (EAMUs required) and Trianum P are biological alternatives for compost applications. Remove and destroy any plants showing signs of dieback and wilting.

Feeding - Change to high-potash (K) products to harden soft foliage and green-up pale older leaves. Use products such as Hortifeeds 2:1:6, Peters Plant Finisher, Sangral 1:1:3, Solufeed 1:0:3, Universol Violet or Vitax 2:1:4.

Vine weevil - Continue adult controls using foliar sprays of Chess WG, Hallmark WZT (EAMU 2008-2944) or Steward (EAMU 2008-2905) onto foliage of vulnerable ornamentals.


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