I have never seen anything like that. Can you take a closer pic?

Sure. It's weird, the tree looks to me to be healthy overall and pretty vigorous. Hopefully someone will know what it's a sign of!

I had exactly the same on a couple of outdoor citrus (ichang lemon and a citrumelo) three or four years ago. It followed some months after an application of a general purpose granular fertiliser (called Growmore) but I have no idea if there was actually a connection with this.

At first I was really excited, thinking I had produced some new and ornamental variegated hardy varieties. But even then, I was suspicious because the growth was several stems at the same time on two different plants, and the new growth looked a bit stunted. A new variegated sport would have been a single new twig.

I tried grafting from this growth, but after a while, new growth on the scion reverted to normal. On the affected trees, new growth also eventually became normal and the 'variegated' leaves slowly dropped off.

So, despite some research, I could find nothing similar described. I feel it was something in the fertiliser I applied, but have no proof. Perhaps a combination with certain weather conditions - too cold, too wet, too dry - I don't know.

Anything in this story sound similar to your problem? Is it significant that these are all hardy varieties growing in cool climates?

Citrange/Mike. Near London, UK.

That's very interesting, Mike. So here are the things we have in common:

Hardy Variety

Cool Climate + Especially cool and long Spring

About a month ago, an application of granular 'Miracid' fertilizer by Miracle-Gro. (I usually use Foliage Pro, but decided to give the trees a shot of more acidic feed instead of using vinegar to see what would happen).

It's been a dry Spring for the most part, but I've been watering more than enough and I'm confident the tree hasn't dried out.

The mystery continues...

What do you mean by "granular"? Did you not dissolve it in water before applying?

Vladimir,

I dissolved the fertilizer of course. I just used granular to denote that it wasn't a liquid feed like foliage pro or protekt. As an aside, I haven't really liked the miracid fertilizer for my container plants. Results have been spotty at best, and it seems to both be easy to over-fertilize and quick to flush out of the soil, but I don't know what else I could use for gardenias or container blueberries. Probably a question for a different forum.

The damage to the leaves of PacNorWreck's tree has all the symptoms of being caused by thrips.

Pac - I thought so. Just checking.

I have been using Miracid on my old (more than 25 years) gardenia and it worked well until this year when it is appearing to be nutrient deficient. But that may be a root issue because it is in sore need of repotting. (One more thing to do.)

Silica, on a scale of "wait for beneficial insects" to "freak out and use all the (Spinosad and Neem) pesticides", how concerned should be I be about thrips? It seems commercial guidance is to leave them untreated unless you see thrip damage to your fruit, but I also don't want them to spread to my other citrus.

Vladimir,

I'm waiting for them to dry out enough, but I'm going to give my gardenias in decline some agri-fos, which has done wonders in preventing root issues for my container citrus. I'll let you know if it helps at all.

I had a look to see if I could still find any sign of this leaf problem on my in-ground Ichang Lemon. Although, as I said before, most effected leaves have now dropped, some were still visible a bit back from recent growth.

See photos here:

http://www.homecitrusgrowers.co.uk/temp/ichanglemonleaves.html

Any number of sucking/salivating insects can cause damage like that. It is likely too late to treat for it now, as the insect is almost surely gone; and the leaf is still relatively good.

Hi John,

Whose tree were you referring to, or were you referring to both? Thanks for your advice!

Both. BTW, while we are on the subject, I am not a big fan of the current "fad" of spraying Neem oil every time there is a problem. Neem is a broad spectrum insecticide and it kills everything, including the beneficials.