year some of the blooms on my lovely dahlias (right) are full of
bugs. What are they and what can I do to get rid of them? I don't
like using toxic sprays so can you recommend something safe?
bugs are black aphids sucking sap from the petals. Serious infestations
can cause distortion of the flowers but luckily they are quite easy
to control. You might find they only affect a few flowers and if
you cut these off and destroy them the others may not be attacked.
However, if they are widespread you may have to take other measures.
There are lots of products available to control aphids, many of
which have low toxicity to humans. Some gardeners find a solution
of up to one teaspoonful of washing up liquid (such as Sunlight)
in one litre of water will control them if sprayed directly on the
aphids. Fatty acid-based products, like Natures Way Insect Spray,
are also effective but again need to be sprayed directly on to the
aphids. The problem with both these sprays is they may damage the
tender dahlia petals, so you could try using Mavrik, a low toxicity
insecticide which is safe to use on delicate plants and has the
added benefit of not harming beneficial insects like ladybirds.
Gardener, Issue 141, 2004, Page 23
Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.