Lichen as a dating tool
This may mean that the following year the plant looks a little better, and it will flower on any healthy new growth.But I doubt if you will see off the problem completely.As they grow in stature, these stocks regularly drop their lower leaves, which can be gently pulled off for aesthetic reasons as they become yellow and ugly.The remaining terminal rosettes of grey, felty leaves get more and more “architectural” as the plant ages and becomes increasingly shrublike.The best you can do is to prune the whole plant back hard onto its wall-cladding framework of branches after it has flowered next spring, thus sacrificing next year’s berries.You will be pruning out the worst of the breeding colonies, and you should clear up every scrap of debris afterwards and burn it.Then feed the roots with a general fertiliser (they will be extensive on such a mature shrub), water it in and apply a thick mulch.
For the past three years, my 14 year-old pyracantha, growing against the house wall, has become increasingly infested with woolly aphids. Woolly aphids that commonly infest trees in the apple family, as well as pyracantha and cotoneaster, are the very devil to defeat.I have sprayed with a hose, and then with a systemic insecticide but to no avail. These super-aphids have worked out a cunning way to survive – covering themselves en masse in a protective greyish woolly coating (that is often mistaken for a fungus of some kind) to keep predators at bay – that includes us and our spray bottles of gunk, of course – and breeding like billy-ho every spring.