I planted a lemon seed 10 years ago and I got a nice little lemon tree out of it. Its more of an emotional thing for me:) I really like the little tree and its more than 1 meter long already.
So recently I noticed that the tree is rather weak and slumpy so I examined it more to see what could be the problem. And I noticed small brownish spots on the tree and on the leaves. Its seemingly some kind of bug egg or something but I'm not sure because I cant spot any actual bugs around the tree which could be eating it leeching his energy away.
Mostly the stock of the tree is having this issue and even there only the green part. The parts of the log which have some treebark too are intact and no brown spots are shown. The leaves are rather intact - only smaller dots are showing there and more rarely.
What treatment should I do? What can be this brown thing and is it dangerous to my tree? How can I avoid this happening in the future?
I definitely see scale, although in a couple of the pictures it looks like there may be something else too. With infestations like this, I often start by blasting the plant with a strong jet from the hose to dislodge as many of the pests as possible. Frequently I don't do anything besides that--just repeat the hosing off treatment every few days for a while until I'm sure everything is gone. But there are insecticides you can get that work against scale as well if you prefer that approach.
The thing is that these "pests" or "scales" are kinda stuck to the tree. I can remove them manually tho but a strong jet wouldnt do the job. Also there arent so many so probably removing them manually would be the best.
What kind of insecticides could I get and would that harm the tree itself too in any way?
Also could you define what is a "scale"?
Also a bit off topic: I would like to cut my tree to give him some shape. Would you guys suggest that? I attached a picture to show how does it look at the moment. I'd think about cutting it around the middle - where it starts to go upwards only.
Do you guys think that would help the tree to get bigger/stronger?
Scale is a type of insect--there are quite a few different kinds and I don't know enough about them to tell you which ones you have. Control is similar for most of them though--if you google for controlling scale you should find some insecticides that will work. Insecticides if used according to directions won't harm the tree, although if you plan to eat the fruits you'll want to stay away from systemic insecticides which are absorbed into the plant tissues and provide long-lasting insect control (Bayer 3-in-1 is one example of a systemic--most common active ingredient is imidacloprid). There are some oil insecticides that will work on scale, but with those you need to be careful about sun exposure right after treatment since the sun could burn oil-covered leaves. Removing by hand if there aren't too many is always an option as well, but I'd still give the tree a good hosing off to clean up some of the other little things that are on there.
Citrus trees are prone to Scale(s), mealybugs, mites, and new to Ca. , Citrus Leaf Miner. Bayer does make a product for fruit and nut trees. It does contain Imidacloprid however. I have tried it, but without much success, and of course timing is everything outdoors. Don't want to kill the bees, and I doubt their claims that state that it won't affect bees. This year I'm alternating all season oil and insecticidal soap to try to keep the bugs under control, but again, timing is tough. Too windy in the evenings, so I have to spray early in the morning before the breeze starts and the bees get out and about, and when temps are supposed to stay cool for a couple of days.
As to shaping your tree; all trees can be pruned to shape, but growing in a window it will keep reaching for the sun. Lemon trees are not particularly pretty shapes to start with, and without full, overhead sun it will tend to get leggy. Hope this helps.