GARDENING
Are your Dahlias a disaster this year? HERE'S WHY AND HOW TO GET BETTER RESULTS By Hannah Stephenson
Dahlias are the divas of late summer but if yours are looking lacklustre, experts offer tips on what you can do about it. As dahlia shows take place throughout late summer, these spectacular plants continue to dazzle, their gorgeous blooms creating a riot of colour. But what if your own specimens are looking tired and forlorn, with damaged leaves and petals or stilted growth? We spoke to the experts to find out how to tackle these problems, with The Cornish Dahlia Society, which is this year staging its 39th annual show at the Lost Gardens of Heligan, offering the first three of the following tips... 1. CHECK IF YOUR DAHLIAS HAVE A DISEASE Fungal diseases (powdery mildew & dahlia smut) are the most difficult of dahlia ailments to remedy. Spider mite is also difficult to deter, but could be treated every 10 days using a horticultural soft soap. It's recommended to remove the lower leaves affected by mildew to improve air circulation. You could also try a milk/water 30/70 solution, which is commonly used to manage powdery mildew on cucumbers and courgettes. Dahlia smut presents as pale spots in the early stages and then develops into yellow and finally dark brown spots. Older, lower leaves are generally first affected.
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Tubers will not be affected so can be lifted as normal and cleaned thoroughly but the spores can contaminate soil for years afterwards so plant your dahlias in a new location the following year. You could also try mulching below plants, using straw, to limit further spread through splashback from the soil on to foliage when rain is forecast. 2. WHAT ABOUT BUGS? Deformed blooms are likely due to capsid bugs. As they suck the sap of plant tips, usually developing flower buds, toxic saliva enters the plant, causing distorted buds and flowers.