Hello everyone,

since April I am the proud owner of my first fig tree (longue d'aout). As I only have a balcony available and it gets very cold here (I am from Austria, would be a Zone 6 in the USDA) the little tree is living in a pot on the balcony for now, with sun from 2pm till sundown.

Since a few weeks, I have noticed that the tips of some of the leaves started paling and then little brown spots formed. In the beginning I thought it was a sunburn, but after some research I found out it actually does not look like a sunburn at all. In fact, it looks like rust, BUT only on the upper part of the leaf. There is nothing on the underside! Also, the climate here is dry and i never water the leaves, only the soil...
Could it be a nutrient deficiency? Should i fertilize it? I have not done that yet since I repotted it by the end of April. I used standard flower soil for repotting, with a good drainage (at least it says so on the package) and have watered it only when the soil was dry a few cm down.

I would be very happy about your advice on this!

I added some pictures:
1. Pale edges and brown spots, there are a few leaves like that on my tree
2. Underside of the same leaf
3. & 4. Some different looking spots on other leaves

It is highly likely deficiency problem, It is fall/winter time in your area, Fig tree need 13C+/55F+, without this temperature, Its root can not suck up nutrition.

Greetings from neighboring Hungary :) welcome to the forum. Soon you will start collecting varieties, this is probably not your last fig tree.

I usually fertilize with "Volldünger Linz", it has a 2:1:3 NPK ratio (14-7-21) that was recommended at some point on the forum, and they seemed to like it last year. 

I don't know if it's rust, I don't have experience with that. I am new to the hobby, I got a bunch of figs last year and all died to frost that I had stored in an unheated shed outside. I have a few left that I was rooting over the winter and some I jsut bought recently.

I fertilize when I remember to do it, mostly on weekends or every 2 weeks. I do keep an eye on the moisture level and water them every day if needed.

If it is fungi, Those spots can be slightly pop out underside, or lots of yellow power falling out from bottom. It is nutrient deficiency, highly likely from those micro nutrient group, you should try Volldünger Linz or other fertilizer contain micro nutrient.

If you can't find it in stores, just get some citrus fertilizer, or even tomato fertilizer. Check the label and make sure it has extra micronutrients like iron, zinc, etc. Follow the dosage instructions, for small plants or newly rooted cuttings use a more diluted version to prevent burning.

Will do, thank you!!

Yes, you should  try fertilizer that you can get in your area, Make sure check its label that it has extra micro nutrients, In my area, we do not have Sun often at early spring, Last week, we has sun for everyday, some of my potted fig trees got sun burned, it looks like your fig leaves as well, keep an eye on new leaves, it should be thicker.

I got longue d'aout last year, however, It was mis label of "Desert king", This year, I got some Longue D'out cuttings, it roots with few beautiful leaves, I like it.

Yes, we have limited sun at early spring, I left them outside 1+ month ago, and they grow some shaded bigger leaves, last week, weather quickly change to sunny everyday and warm up, Some leaves burn, However, lots of new leaves and new branches appear now.

I had rust problem for Lattarula italian hoeny tree at late summer/fall while other fig trees was fine,  I can not find neem oil to treat them, I try not to wet its leaves at all this year,  I hope that it reduces rust problem, Most rust problem happen at end of summer/fall here.

Last night, I saw lots of bady garden spiders on trees, It is mite season, I check fig trees leaves with 50x microscope and I find FMV mites, I sprayed them with very extremely weak insecticide, our country ban most insecticide including neem oil, I left potted trees in unheated shed last winter, Temperature was down to -9C/15F, FMV mites is still alive,  They are quite tough, because of this, I will not get any more fig trees until I am sure that I can control this mites problem.

Due to different location, I hope that someone near you can help you out.

Looks definitely like rust to me. The leaves don't have to get wet by rain or watering to develop rust, high humidity levels in the air can trigger it. But usually you don't have to do anything about it, as long as the newly developed leaves stay healthy.