The case of the black moss

A couple of years back I planted a fever tree outside our gate.  The tree never really took off.  It didn’t die or look sickly, it just never seemed to grow.  I put it down to the fact that the soil I had planted it in was this terrible, sandy, red earth and decided to give it some time to come right.

However, earlier this year, I noticed a black moss growing on the trunk and branches of the tree and thought I better do something about it.  First I Googled black moss but didn’t come up with anything useful.  Then I went to take a closer look at the tree and noticed hundreds of small, black ants moving up and down the tree trunk.  Could the ‘black moss’ actually be the ants footprints, I wondered?

After a bit more Googling, I found something that surprised me.  Both the ants and black moss were indicator species, pointing to the real culprit, aphids.  I went back to inspect the tree for a third time and lo and behold, there in the leaves, were hundreds of tiny aphids.

So, in pulling all the pieces of the puzzle together, I worked out that the ants were protecting and ‘milking’ the aphids for their carbohydrate rich excrement, called honeydew.  This was also coating the trunk and branches of the tree, providing a perfect environment for the black moss to grow.

Solution, kill the ants and let the aphids natural predators control the population.

Result, the fever tree has suddenly sprung to life.

New leaves sprouting on the fever tree.
New leaves sprouting on the fever tree.

10 thoughts on “The case of the black moss”

  1. Hey Niall, this is also usually a sign that the soil is not great, which puts the poor tree under a bit of stress, and so it becomes more prone to pests and diseases. If you dig in some compost around the base and give it plenty water – the aphids won’t come back.
    Uncle Google is one of my best friends too…

  2. Fever trees also take a long time to establish a root system to support them when they grow tall.

    My dad planted one in our front garden and for years it remained healthy but leetle. Then, almost overnight, it shot up and is now big and beautiful ๐Ÿ™‚

    My dad always had faith that it would reach its potential – an essential element of gardening I would think…

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