Identification: Indoor Avocado - Strange dots on leaves

Hi all

I joined this forum in the hope that someone who knows about indoor grown avocado trees might be able to identify these strange black dots in the attached photo (you may need to zoom in to see them). Please ignore the burn marks on the leaf, as that was due to an unfortunate over-fertilizer incident when I left it with someone for the summer...

I've grown this avocado tree from a seed and it's about 2 years old now, and is growing happily, however over the last few months these little black dots seem to appear along the veins, followed by discoloration/flaking of the green part of the leaf. I've tried changing the soil and repotting it, also cleaning the leaves with soapy water. The plant is still growing and not really showing any other side effects. Also these dots appear over very slow periods of time, so I've been thoroughly checking each leaf every week or so. Finally, I can scratch them off with my nail when I spot them.

Any help would be greatly appreciated! I've been cutting off leaves when the 'rash' (for lack of a better word) gets too excessive, but I can't keep doing this forever or I will have no plant left at the end of it!

 

I can't tell, but suspect this is an insect of some sort. Thrips would be one possibility, but when I've seen them they are under the leaves. Scale comes in different colors and sizes, so they might be a better fit for something you can scrape off with a nail.

 

The description of the dots reminded me that many years ago I had what I described at the time as poppy seeds over some plants and even my walls. I have no memory of how I got rid of that, and I never did learn what it was. But I looked up "poppy seeds as garden pests" and came up with frass, which is the excreted pellets of caterpillars or other insects. Maybe the insects are under the leaves, but dropping the pellets onto the leaves below.

 

Thanks for getting back to me! I hadn't thought that it could be something falling from under the leaf above - I will keep an eye out, however I have generally thoroughly checked all leaves and so far haven't spotted anything. Describing it as looking similar to poppy seeds is quite accurate, just smaller and flatter.

 

Those look like Avocado thrips.

I've had them on my Avocado tree (I suspect that they came from store-bought Avocado fruit, as Avocados with scarring may carry the pest).
I've sprayed with Safer's End-All (which stated efficacy against thrips), but now only Safer's End-All II (which does not cite thrips) is all I can find. It seems to worth though.
I usually strip all the affected leaves and spray remaining leaves and stems.

If you Google "Avocado thrips" you'll see the silvery damage done to the leaves and the scarred fruit to avoid at the supermarket.

 

Excellent help! It is hard to tell from pics, but your experience with a pest that could have caused this is much appreciated.

 

Hi!

Yes! I googled an image and it is exactly what it is! Thank you so much, as recently although my plant is growing these have started to appear again. I'll have a look online and see if I can find that spray you referred to here in the UK.

I will update once I've had a look.