Is this myrtle rust?

[Mango Stein]

Small number of affected leaves on feijoa and pitomba.

[fruitlovers]

No that is not myrtle rust.

[Mango Stein]

Thanks Oscar.

I guess the next questions are, what is it and should I remove the leaves.

[BMc]

Pitomba gets a related rust and can gets lots of die back. A friend treats as if it's phytopthera and has had great results with phosacid. You'll be able to tell if you get the real myrtle rust. It's bright yellow. Just noticed a fresh infestation on an araza boi that had otherwise looked very healthy.

[Don]

The leaves on the bottom look like they could be burn, sometimes if I cant water till middle of the day I will get burns on the lowest leves where water has landed on them and the sun magnifies through water and burns them. They will just fall off, no drama.

[fruitlovers]

Thanks Oscar.

I guess the next questions are, what is it and should I remove the leaves.

Yes would be good to remove and dispose of leaves. Not sure it is a disease. Could be something as simple as nutrient deficiency also.

[Solko]

It looks like fertilizer burn to me. Are you in a colder climate zone? And did you fertilize before winter came? All my Myrtaceae that overwintered outside look like that. They get the spots when the weather gets really cold.
I think what happens is that the slow release fertilizer keeps releasing fertilizer in the ground with every rainfall in winter, and the roots keep taking up the nutrients, but the top part of the plant has stopped growing or is dormant, so there is an inevitable build up of nutrients inside the plant. And the salt build up shows up as deep red lesions on the leaves.
This may be a particular problem to evergreens that keep their leaves in winter, but slow down or halt growth.

Now that the temperatures pick up and the plants are actively growing again here, all new leaves look healthy, so I don't think it is indicative of permanent damage, or a real problem. But the lesions may make it easier for fungi to establish on your plants.