Dieback and cankers on fruit trees

One of the signs you may have Phytophthora, or root rot disease, is the appearance of these summer cankers on your fruit trees.

Phytophthora canker on plum tree

Though the disease comes from the roots, the dieback starts at the top of the tree, and these cankers usually become active during summer.

A peach tree with dieback from Phytophthora

It’s a nasty disease, and is responsible for many fruit tree deaths. But fear not, in many cases it’s perfectly beatable.

Of course the answer is in the soil!

A toad enjoying our healthy soil

Phythopthora is a fungus that lives in water in the soil, so it thrives in wet and waterlogged conditions.

But guess what eats it? Other soil fungi, the non-disease causing kind!

Healthy, well drained soil with lots of organic matter is the perfect breeding ground for these healthy soil fungi, and they will out-compete the Phytophthora.

This nasty soil fungus has been one of our main setbacks on the farm, particularly after the flooding rains we had a few years back. We lost a lot of trees, but our soil improvement work helped us to save a lot of sick trees we thought we would have to pull out.

A peach tree showing lots of new growth as it recovers from Phythopthora

The key to our soil improvement regime is (a) increasing the organic matter in the soil, and (b) making sure we have active (healthy) soil microbes doing their work! This is what we use:

  • compost (just spreading compost on top of the weeds or grass is good enough, as the worms quickly incorporate it into the soil);
  • compost tea — we aim to put it on at least three times a year (though even more would be great if we had the time);
  • microbe food — things like fish, kelp and humates are put through the irrigation system to feed the soil microbes;
  • occasional soil remediations, e.g. calcium.

Soil improvement is a long, slow, continuous process, but we’re consistently seeing improvements, so we know we’re on the right track!

You’ll find more information about how to identify and treat Phytophthora (and other common fruit tree diseases) in our short course “Keep Your Fruit Trees Free from Disease“.

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