Jackie French: Are your plants trying to tell you something?

Plants have their own ways of telling you there is something wrong, sometimes obvious, but usually gradually and subtle.

We've just had the tree loppers to cut down the liquidambar by the fence. It's sad to see it go -the red autumn leaves are a delight. I had no idea there as anything wrong with it. It had plenty of leaves, green in summer, bright red now. Then I noticed a massive big bracket of fungi that had suddenly grown at about waist height. I had a closer look.

And there it was, not obvious to anyone. Unless they looked closely - rot that seemed to go well into the tree, and a single suspicious black line going right up to the tree top. If the tree fell in the wrong direction it would squash the bedroom, the fence, the shed or any passing human or wombat.

A rotting tree that big means tree loppers. I can cut a tree down, but I can't climb up one and cut it down in small manageable chunks so there's no danger of the whole tree crashing down in the wrong direction.

The tree loppers did a magnificent job, cutting it slice by slice. Danger averted. They then cut down a few apple trees that didn't survive the last drought.

I thought those trees were fine too - they leafed up beautifully as soon as it rained. But much of their roots must have died in the heat and dry. The dead wood became infected with fungi, the fungi spread, and this year they put out a few leaves which browned by mid-summer. The branches snap, rather than bend, a clear sign of a deceased tree, and the long line of toadstools along where the roots are underground is yet another sign that the tree has only another year or so, with luck.

I wish humans grew toadstools to indicate health problems. It only took 30 seconds to diagnose that tree. No crowded waiting rooms, no mammograms, no prostate checks, no colonoscopies, just extremely small toadstools to show the location of the problem, and maybe the right colour to diagnose it.

The doctor would only need to glance at your fungi ."Ah, I don't like the look of those tiny blue mushrooms on your right hand side - they're a sure sign of a grumbling appendix", or "The bracket fungi on your shoulder has nearly vanished. Keep doing the exercises and you should be right as rain."

MORE JACKIE FRENCH:

If you are at all in doubt about any trees that might fall on the house, the car, or passers-by, hire an arboriculturist. Other useful signs of root rots are yellowing leaves. If the older leaves are yellow and the new ones greener, your plant needs nitrogen - or more water in a drought, or less if the soil stays soggy too long

Phosphorus-deficient plants have smaller leaves than normal; the leaves may droop and look generally sad and unthrifty; and you won't get growth spurts in spring and after rain when you expect it. The fruit may taste sourer and vegies slightly more bitter.

Symptoms occur first in the older leaves - they'll be bluish green or purple and not as bright as the new leaves, and there may be brown scorching along the leaf margins.

Plants that are deficient in potash are not as frost hardy - it is worth adding potash-rich materials to fruit trees or roses in autumn (i.e. NOW) to help protect against the effects of late spring frosts. Hen manure is a good source of potassium, but is also high in nitrogen, and your new growth from a sudden burst of plant tucker growth may be frosted off.

Trees may also die off (ie sport yellow leaves and dead wood) when its natural lifespan is up. Borers are a sign your trees are getting old. You can poke soap mix with eucalyptus oil in the holes to kill those particular borers, but more will arrive. Leaves that vanish overnight are probably now being digested by a dozing possum.

But if you are in doubt about the viability of a fungi-decorated tree, sadly, you are probably right.