problems with grafted citrus trees

[incubator01]

Hi,

For 2 years now I am tirelessly trying to keep citrus trees alive, but so far I managed to kill 8 already
I buy grafted trees which are probably no older than 2 years from a local vendor who sells exotic plants, he gets them from growers in sicily, Italy.
I bought Kaffir limes, Key limes, persian limes and limequats and from other sellers I bought cuttings of kaffir lime and persian lime.

The internet is full of different kinds of information which is very contradictional and caused much grief.
First trial was with a kaffir lime put in purchased potting mix for citrus plants, the plant was grafted and eventually died from rootrot and armoured scale.
Because people said this kind of soil was not good I found a Dutch site describing to use 50% white sand and 50% compost, but that soil instantly killed the next 2 plants because that soil did not drain at all and remained very wet for weeks.
Third trial was with another Kaffir lime and Key lime using a potting mix of equal parts of perlite, vermiculite and coco peat or peat moss (but I prefer coco peat), that soil appeared to be needed in very hot climates such as South california but definitely not in central Europe, soil stayed too wet because the vermiculite retained moisture too well, but it did drain much better.
However, plants died after a few weeks.
Note that in the second and third trial I washed the old soil off the roots with water, probably this also stressed the plants too much.

Last test I re-used the soil from the vendor's pots and added a bit fresh potting mix and compost, so basically the composition was: equal parts of potting mix (universal), regular soil with sandy structure and I added perlite to improve aeration.
This time I did not wash the old soil on the roots and just loosened the roots on the edge of the root crown, left the soil on the rest so stress would be minimal.
I put it in a pot that was 10cm bigger (wider and higher) than the previous one.
After one week the kaffir lime and persian lime dropped all leafs, some branches turned brown, even though I reduced my watering regime.
I let them dry out (not fatally) and give it little bits of water once a week, then they start to grow new foliage, but more branches die off.
Weeks later the new foliage is nice and big, suddenly the plant stops growing, new buds wither and turn brown, some tiny green leafs fall off.

In  the meantime I also got a limequat, repotted it the same way, it was fine for 3 weeks, then suddenly one day when I was supposed to water it, 90% of its leafs were dried out and fell off. Some healthy ones too for unknown reason.
The food I give them is Floranid Twin Permanent with NPK of 16-7-15, which turns out to be the best slow release fertiliser compared to all other liquid ones I tried.
There were no aphids/scale present on any of the plants.

To this end I am slowly to the point of breaking down and giving up on these grafted horrors. I know growing from seeds is not done in commercial  areas because of viruses passing on but germinating lime seeds is more successful than keeping those trees alive...

But regardless I wanted to find out if there's anything different I can do.
As for the location: 2 years ago I put them outside, that tree could withstand bright sunlight, until I repotted it. After many attempts to get the information out of the vendor, I now put it in my greenhouse (where it's warmer) where there is a shade cloth to protect the limes from burning sun. The roof of the greenhouse has partially filtered glass so no bright sunlight can get in. The vendor told me he put them in there too with similar conditions, even when it was very hot.
So it is sheltered from wind there and gets filtered sunlight, protected from the western sun.

Attached are pictures from a kaffir lime, persian lime and limequat as they are right now.
-> Kaffir lime

-> Persian lime

-> limequat

[brian]

Have you ever had your water tested?  I can't think of anything that would cause such a rapid decline in free-draining soil if plants are throughly watered.   If it is drowning, the leaves will turn yellow and drop off.  If it totally tries out, the leaves will dry out, roll up, but stay attached the the plant for a while.  Fertilizer burn, chemical sprays, drowning, drying out, intense sun, could all kill a plant quickly.  Lack of fertilizer won't kill it quickly.

If you buy a plant from this nursery and don't repot it or otherwise disturb it, and simply continue to water it as needed and place it in part-shade, does it decline quickly??  You may be introducing too many variables at once. 

[Millet]

How free draining is the medium that the tree is planted in?

[incubator01]

In the previous plants that died, it was most definitely rootrot (Phytophthora?) because when I removed the dead plant from the pot the roots where full of fungus spores. (I tried a fungicide on one of them when it was not dead yet but that didn't work) and they also had the orange crystallised resin coming out of the stems.

On the current ones, they only have had leaf drop and brown branches, no resin.
The water I use is rain water or tap water (I used both), neither of them contain calcium , this is why I make sure to add CalMag but that didn't help either.

When I leave the plant in the pot from the nursery, the plant remains stable, however the seller did mention I really should repot it, and when I did I noticed why. The plant was container bound, the roots were really in an urge to get out of there and tied in a knot because they were unable to expand.
When the plants were purchased the leaves of the kaffir lime did show some yellow / greenish, probably from a lack of nutrients because the soil was well watered.
If he would over water the plant then it'd die in his nursery but he claims they dry out really fast in his greenhouse.
The time of repotting didn't seem to matter, I repotted a persian lime in spring and in summer and both suffered the same fate, the first one died though.

I also tried different kind of containers, first mostly plastic ones and lately, the limequat a terracotta one because it absorbs moisture better. but as you can see it doesn't improve things.

For the limequat I was wondering if drought might have been a problem but there was so little time in between, on a Thursday it was still moist enough (I use a cheap € 10 moisture meter from amazon because it's more or less good enough to figure that out) and on Sunday it had most of its leaves dried up, the weather was warm but not so bad it'd dry up everything, usually it takes a lot longer to dry up the soil. The other 2 limes were not dried out at all so that was proof the weather couldn't have done it.

As for how free draining the medium is: the middle section of the soil is the one of the vendor, it is pretty free draining, when you water it it runs through it instantly and when you water more than it can absorb, it definitely runs through the pot holes quickly. But the soil retains the absorbed moisture pretty well, when washing the roots with earlier plants I noticed the soil becoming a clump of mud that would stick to it really well.
Around that I put my soil, a mixture of a bit of compost, universal potting soil (DCM) which contains some peat moss, some of the vendor's soil from previous plants and perlite for improved aeration.
I noticed that my circle of soil dries out faster than the core. But washing the root ball out is so stressing for the plant that I don't do it anymore

[brian]

It is hard to say, it sounds like you are taking the right approaches now.  I would try isolating variables by only changing one thing at a time.  Buy a plant, don't mess with it for a few weeks, see how it does.  Then repot it into a slightly bigger pot with new soil, but don't disturb the roots.  Wait a couple weeks.  Fertilize, wait a couple weeks, etc. 

In my experience with 100+ container plants of all different types and sizes (mostly citrus), they do just fine with moist, well drained soil and seasonal application of granular slow-release fertilizer, and regular watering.  The biggest mistake I made in the early years was using too much peat moss  or other heavy soils and plants drowned. 

[incubator01]

That's what I did with the kaffir an persian lime of which I attached an image, I waited about 3 weeks before repotting, however I'm afraid wrong advise from someone else caused this rootrot. He told me to put pine bark on top of the soil to protect the surface roots and retain moisture, problem is that pine bark makes my soil too moist and even wet for weeks.
I simply hope these 2 will recover permanently from it, so far they went through the worst, but it's still not 100% out of their system.
Maybe yes if I did buy a new one and did it without the pine bark  it would be fine.
However I'd much rather get my hands on viable kaffir lime seeds because I prefer a larger growing tree with thicker trunk than a grafted one, people keep telling me grafted trees don't live as long and are more prone to rootrot.

[Millet]

There if nothing wrong with using pine bark in a growing mix.  Very many growers use the 5-1-1 mix = 5 parts pine bark , 1 part peat and 1 part sand or perlite. A 5-2-1 medium is also a good medium.  Laaz uses a 50/50 mix of Turface and peat.  In reality, it is not the water that does damage to citrus roots, what actually causes damage is the lack of oxygen.  Citrus can be grown in pure water, as in hydroponic culture.  What is of up most importance that the medium is a free draining medium that provides a higher level of root zone oxygen, while still providing proper amount of water.

[incubator01]

I did come across some guides of the 5-1-1 mix and I  was once eager to try it but the problem is acidity and nutrition, they say I have to add a part organic lime to it but i have no idea under what brand that is sold here (I do know what it is from looking it up but its the english terminology that makes it hard to map it in local brands)
And nutrition because there's not much nutrition value in this. If I have plenty of seedlings that germinate I'm eager to give that mix a try on one of those but only if I know the belgian equivalent of organic lime and if I know a slow release fertiliser will suffice (Floranid twin permanent is a dry fertiliser that lasts about 4 - 6 weeks)

EDIT: If plagron calcium kick is organic lime ( https://www.plagron.com/en/products/calcium-kick#:~:text=Calcium%20Kick%20is%20a%20pH,makes%20the%20plant%20grow%20faster. ) then I am already familiar with this product, if it is not then i need further guidance.

However I would need to know how frequent I need to water the plant then (more or less, I know a fixed irrigation schedule is not always good, just to get an idea of how often to check it), because my moisture meter will not function very well in such a mix.
Also, if i were to use such a mix on an already purchased citrus tree with that thick lump of soil from the nursery, is it really a good idea to wash it of? last attempts were very stressfull for those plants and some say not to do it while others do.

At least it is good to know this mix does give good results with others beyond the Youtube video

[pagnr]

To adjust pH of growing media you would use Calcium carbonate lime and Dolomite lime. The rate is around 1kg to 2kg per cubic metre of each,depending on the pH adjustment needed. These are derived from grinding rocks so are permitted organic inputs.
They also supply Ca and Mg. Once you get the pH correct around 6 to 6.5 other trace elements should be in balanced supply. If the pH is far too acid or alkaline, you are potting into toxic mix which will cause root problems. Peat and Pine bark can have lower pH than coco peat. I use about 33% coco peat in mixes.
Correct pH of mix solves a lot of problems.
Do you add fertilizer when or soon after you repot ?  NPK of 16-7-15 is reasonably strong for young plants or fresh repots.
Usually for Citrus in pots the P level could be a lot lower, say 2 or 3
I would wait to apply fertilizer or lower the rate until they take. What is the N source of that fert ie Ammonium, or Urea or possibly Potassium Nitrate as it has a high K value??
High N can cause root burn causing rot symptoms.
The same potting media can behave differently in different pots. You need to balance Aeration/Air filled porosity with water holding and drainage.
For Citrus I prefer taller narrow pots, try to repot into the upper 1/3. The mix can be watered frequently but drain well and the roots are out of the soggy zone.

I don't think you can see most root rot fungal spores without a microscope. If you can see fungus spores in the mix, it could be woodrotting fungus from uncomposted or poorly aged components.

Have you tried growing other plants in your mixes ? A simple test is to grow 100 radish seed of known germination % and count the survival rate. It should be close to 100 %

[Ilya11]

Where are you in Belgium? If you speak French, read recommendations on forum Agrumes-Passion, there are many people from Belgium that successfully growing citruses.
Basically, I guess your problems are in roots, pots should be very aerating, citrus roots outside soil need a lot of oxygen to withstand  diseases. Most of citruses from Sicily are delivered in heavy clay, because they were grown in fields. In majority of cases the vendors are washing this soil, but just add some light substrate outside. The water is easily draining but the clay is becoming dry. So you should wash this clay on delivery.
Than the easiest way is to use a cheap pine compost that is always available in supermarkets, check it before, it should still contain some granulation. If you want to use something else avoid "Citrus" substrates, majority of them are very bad. Instead, a good commercial substrate for potted plants with addition of equal volume of perlite  should be fine.
To assure aeration, some people here are perforating the bottom sides of plastic pots with holes of ~1 cm and the same distance between them. You should not put any drainage matter to the bottom. To fill the gaps between roots just use water  flow. 
For the fertilizer- most so called citrus fertilizers in Europe are not appropriate. The closest to ideal is Feriligene fertilizer for geraniums  18-6-12  with Mg and microelements.

[incubator01]

I'm from the flemish part of belgium, i knew about the french forum but my french is too limited for me to make too technical conversations. So that's why I'm here

My pots (the plastic ones) have a lot of hols in the bottom, I drilled 8 extra in addition to the 12 existing. My drill  is a small one so doesn't support 1 cm drills, the biggest it canhold is 8mm diameter.

As for a cheap pine bark compost, the only compost i found in Gamma is https://dcm-info.com/int/en/products/soil-improvers/vivimus/dcm-vivimus
It's not exactly what you mention though, and not very granular either.

The fertilizer i have should do however, the vendor has been using it for years on all his citrus trees and I'm even using it on lemon and limequat seedlings and they grow nice.
But it is true that most easy to get fertilizers are not good here, hence I order the floranid twin permanent elsewhere.
The mix of a commercial substrate plus perlite is also what I do for my seedlings, I use https://www.eurotuin.be/dcm-potgrond-voor-huis-tuin-60-l-92711796?partner_id=commerceconnector&utm_source=TradeTracker&utm_medium=feed&utm_campaign=ShopForward+BE+Shopping

[Ilya11]

Not this substrate, but even cheaper one, typically in France it can be found in Aldi supermarkets. Actually, home made compost can be also used.
The holes should be not in the bottom, but on the bottom part of side walls. You can make them with electric drill.
The spacing between them could be up to 10 cm

[incubator01]

ah, I once thought of that but never did, but i'll go do that
thanks!

[Citradia]

Someone may have already mentioned it above, and I guess you already know, but if you’re using sand in your mix, make sure it isn’t play sand. I’ve learned that play box sand has salt in it that kills plants.

[Millet]

I use Calcium Nitrate CANO3 to supply calcium to my 5-1-1 mix.  Most city water contains enough calcium to supply citrus trees.