What is causing ‘Wet limbs’ on olive trees?

Sometimes we see some things happening in the grove that appears out of the ordinary…. this is one of those…  I have received a letter with these photos:

“Hi Amanda, We were wondering if you can tell us from the attached images if the markings on the limbs of these Barnea olive trees are a problem ??

Last year we pruned some of the Barnea Variety as part of our ongoing programme and noticed the marks on only the pruned tree while harvesting, but not all limbs.

The olives on the pruned trees are large and excellent quality while on the un-pruned is smaller but more plentiful.

We appear to have overcome last year’s problem and in fact, have exceeded our previous best yield with still plenty of quality fruit to go.

We just want to be sure that there is not another problem developing that we may have to overcome.

If you recognise a known problem will you let us know what we can do to overcome it? We will probably prune off the limbs that are affected where it has no impact on the shape of the tree, but would still like to be able to rectify any problem that may be developing.  Thanks, G.P.”

See what Plant Pathology had to say;

Those symptoms look like an infection coming from the pruning wounds. It’s hard to say what the cause is, but I recall isolating a bacterium from similar symptoms (Pseudomonas syringae) in young olive trees when I was working on an earlier project.

However, it could be another ‘opportunistic’ bacterial infection or even a fungal infection.

What to do?

Remove the damaged limbs and using a lime sulphur or copper application directly to the wound after pruning (sprayed or painted on).

What to avoid?

Avoid pruning when wet weather is expected as that will increase the risk or infection.

If you have something strange happening in your grove, please send photos via email:  sales@theolivecentre.com.au

More about Pest & Disease issues

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