Will Stonehenge Become Reform's...
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No best answer has yet been selected by scluff. Once a best answer has been selected, it will be shown here.
For more on marking an answer as the "Best Answer", please visit our FAQ.I will assume the mould or soot you refer to is a deposit on the leaves and not the bark.
"Sooty mould", is the result of sap sucking aphids that exude a substance known as honey dew, which coats the leaves and is later colonised by the fungus known as sooty mould. The mould itself is fairly harmless, appart from filtering out some of the light and looking unsightly. To rid this you need to control the aphids that produce the honey dew. Various brand named products, in the form of chemical and none chemical sprays can be purchased from garden centres.
Its also posible the holly bush/s could be coated in traffic grime if you are near a busy main road, in which case a regular high pressure hose down should do the trick,and this method is also a cheap alternative to getting rid of aphids, when they are active in the summer..
logman
Thanks for the info. I live in the country so don't think traffic has anything to do with it. When I prune the holly in the spring, the inside leaves are black with what appears to be mold and some of the leaves are yellowed or dead. It puts out new growth after pruning which covers up the unsightly inside. I plan to do more severe pruning this spring and would like to get rid of the mess
Hi sluff, Just a word of caution, i dont think it would be a very good idea to prune your holly as early as spring, as thats when the sap is rising, this may cause the cut branches to "bleed" which can weaken the plant and leave it open to infection and possibly ths sooty mould you have been getting.
I would wait until we are at least well into the summer before any heavy prunning on your holly..