Cool, damp conditions at this time of year increase the risk from a range of foliar diseases including rusts, leaf spots and powdery and downy mildews – whether on crops such as pansy and viola, cyclamen or primula; or on stock being overwintered, in unheated tunnels for example.
One that’s particularly damaging and difficult to manage is Botrytis, which is why I’m having a look at it in this first blog on the disease issues you need to be on top of through autumn and winter.
Sound cultural practice is the first line of defence for them all. Adequate ventilation and air movement will avoid zones of high humidity, which favour foliar diseases, building up in glasshouses or polytunnels. You may want to consider installing fans if you haven’t already – even with the vents open it is surprising just how little air movement there can be over quite large areas, especially at floor level.
Good plant spacing helps too, especially in crops with relatively dense arrangements of foliage where diseases like Botrytis can get established thanks to the humid conditions within that canopy.
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https://www.syngentaornamentals.co.uk/blog/advisory-blog/keep-seasonal-leaf-diseases-check
