Elm leaf edges lose color

hi,
I would really appreciate your help.
In the last month, couple of my trees ( mainly elm, acasia ) have developed a problem
It starts from the leaf edge that lose color, and then most of the leaf lose color ( only the veins remain green )
it's summer time now - very hot, the trees after a big growing
I suspect it is magnesium deficiency, but not sure…
A close up image is attached
What do you think ?
10x for any help
alon

hi,

i think it is a nutrient deficiency for sure, the one we read about most often is magnesium for turning healthy leaves yellow but it could be a general decline in the nutrients available for the tree.

you you use a rich or poor soil for the tree ? and do you feed regularly in the growing season ?

cheers Marcus

Marcus - 10x for your prompt reply.

this elm is in training, the soil is a mixture of mostly peat & tufa ( in diffrent particles size )
I do feed regulary in the growing season with a balanced fertilzer ( npk + micro elements )
the big change is that i have transfered the trees to full sun
maybe this has caused them to grow very strong and they need more fertilizer...
another factor is the heat - the tempeture in mid day can reach 35 celcius...

I have several questions :

1. how can i know it's magnezium deficency, and not other defecency ( for example : iron )
2. if it is magnezium defecency - how do you propose to solve it ? maybe adding Humus ( worms product ) to ferelize the soil ? or maybe i need to buy and apply epsom salt ?
3. maybe the full sun + heat is too much for the elm ?

hi,
i dont think it can be magnesium as you are applying balanced fertiliser - i was going to add 'sun bleached' to my original post so as an experiment put shade netting over the effected trees - two things could happen - eather all the leaves will go green, or the new leaves will stay green and the old ones may stay yellow !.

if the tree does not improve under shade an application of epsom salts should make the tree go very green.

If the tree does not improve under shade an application of epsom salts should make the tree go very green.

Epsom salts is magnesium sulfate.

You have your tree potted in tufa. Tufa is limestone. The soil pH is probably way too high. Until you can repot, feed with an acid fertilizer (fertilizer for evergreens, camellias, etc.). And yes, if you have an excess of calcium, you probably have a magnesium deficiency.
Iris

10x for everyone for their help

Iris - I wrote "tufa" but I'm using tuff
so there shouldn't be any problem of calcium

so i'm still not sure what caused the problem, and what is the problem, and how to solve it

That picture is a dead ringer for a cultivar of Chinese Elm called 'Frosty". It's a varigated form of chinese elm with white edges on the teeth of the leaf. I wouldn't suspect any chemical deficiency at the moment, just a natural cultivar. If it is 'Frosty" it will have the varigated leaf edges most of the early spring and then turn a regular green as the growing season progresses. I'd like to see the leaf of the accacia to compare with if you have one.

Here's a link to a picture of 'Frosty' on Wikipedia
http://en.wikipedia.org/wiki/File:RN_Ulmus_parvifolia_Frosty_leaves.JPG

Randy

10x for the time your'e putting to help me

i've looked at the reference image you have provided - it's not my case.

in my case the diffrence are :
1. it starts from the edge, but after a while the entire leaf becomes white/yellow ( only the main vein remain green )
2. this problem started only a month ago - after the spring "boom" - so I think the tree can't sustain the amount of foliage they have produced in the spring
3. it also happening on other tree types : I will take some pictures and show

in the meantime i've done :
1. added Humus to the soil - to fertelize it
2. added some iron
3. put some partly shade on the elms

it starts from the edge, but after a while the entire leaf becomes white/yellow ( only the main vein remain green

That is classic CHLOROSIS.

I refer you to: http://en.wikipedia.org/wiki/Chlorosis for all the possible causes. You have added iron, so that probably rules that out. Magnesium is the next most likely cause. Epsom salts (tablespoon/gallon of water) will help provide that. You may have other causes -- or a combination.

according to your expirience...
when the adequate defecency is addressed...
1. will the affected leaf that turned yellow in the edges return to be green ?
2. what is the time frame that i'm supposed to see the change ? 2 days ? 1 week ? 1 month ?

My experience with chlorosis & other leaf problems is that once the problem is corrected, the old leaves don't change very much, but the new leaves come in normal, so it will be a matter of weeks or months to see progress.
You say you are using tuff, a volcanic gravel, in your potting mix. Check to make sure it is not contaminated. Do you wash it thoroughly before using?
Humus is not a significant source of nutrients. Are you fertilizing regularly with houseplant fertilizer?
Iris

regarding the tuff:
1. I do NOT wash it thoroughly before using - didn't know I need to
2. how can I Check to make sure it is not contaminated ?

regarding the Humus - the common belief of bonsaist around me is that it does provide a significant source of nutrients and fertelize the soil - can you please explain ?

I do use houseplant fertilizer regulary ( NPK + micro elements )

i'm learning new stuff

10x

theBalance wrote:regarding the tuff:
1. I do NOT wash it thoroughly before using - didn't know I need to
2. how can I Check to make sure it is not contaminated ?

Wash it in a sieve or colander before you use it.

theBalance wrote:
regarding the Humus - the common belief of bonsaists around me is that it does provide a significant source of nutrients and fertilize the soil - can you please explain ?

This impression probably arose because organic matter, which is what humus is, improves the ability of the soil to hold on to nutrients & make them available to the plant. In growing bonsai, we are always trying to balance this with the ability of the soil to provide quick drainage. In Israel, you probably need much more organic matter in the soil than we do in Europe or eastern North America.
Iris

Iris - 10x for the good info !

the acacia with the same problem is in the following image :