Kitchen Garden Forum

Not a veggie question but I have several beautiful but elderly azaleas whose stems are becoming covered with lichen which is particularly visible in winter. The stems seem to be growing increasingly brittle and I'm unsure whether this is because of old age or whether the lichen is in fact suffocating the plants. As I don't want to lose them I'm wondering whether some time spent trying to clean off the lichen with an old toothbrush would improve their health or whether the lichen is not affecting them in any way.

Ello Primrose. I have lichen on aged honeysuckles in my garden. It doesn't appear to be affecting them in anyway. It also grows on an extremely ancient apple tree on my allotment! Alot of lichens are very slow growing. I wouldn't risk brushing it off for fear of damaging the bark, which in turn, would encourage other diseases. I've had look through my various books, none of which list lichen as a disease or say if it is detrimental to the plant on which it grows. I haven't googled it though- am still new to computers and their magic so still tend to refer to my trusted and beloved books! I will "get with it" eventually! Cheers, Elaine.

thanks Elaine. I haven't been able to discover much about the effect of lichen on plants but as it is quick thick on some of the stems I'm concerned about the plants' ability to absorb water in dry periods, which I assume is one of their functions, as well as drawing it from their roots.

PRIMROSE
Do not worry about the lichen, certain types of plant like apple trees and pear trees are favoured host to lichen, the lichen take nothing from the host plant it is also an indicator of clean air.

Lichen just grows ON, not IN the stems.
In woodland with clean air and a moist temperate climate the branches can be absolutely festooned with lichens.

Lichens are a symbiotic mixture of fungi and algae. As Peter says, they are not parisitic, and do not affect the plant - after all the majority grow on non-living things such as rocks.
If you want reassurance, have a look at the RHS advice.

Hi Primrose,
Because of the clean air and the humidity at 500ft most of my trees have masses of Lichen on them and they seem to all be very healthy.
JB.

Well, could you folks please not mention the clean air theory too loudly as we're directly under one of the Heathrow flight paths and I'm claiming aircraft air pollution as one of my reasons for objecting to the Third Runway!. Some days you can actually feel your eyes smarting when you're out in the garden as they fly over so I'm amazed any lichen manage to survive at all.

Dear Primrose, i wouldn't worry about the Lichen, unless you find it growing on yourself, this will mean you are moving too slowly.

Perhaps the lichen likes the mist of Ryan's Gold or don't planes work like trains?