I planted cedar, trunk and branches become black. How can I control the...

Asked July 8, 2014, 8:57 AM EDT

I planted cedar, trunk and branches become black. How can I control the problem? Thank you in advance.

Outside United States trees and shrubs tree care tree diseases

4 Responses

Hello. Thank you for your question. To better help you determine what may be done, I would ask for more information. What kind of Cedar tree and where is it planted? In Canada or a European country? Or Asia Australia? Growing conditions will make a difference. If you can send a photo it would help. Thank you, with regards.

It is Blue atlas cedar ( Cedrus atlantica Glauca) 6 m high. It's planted near building. Temperature during the day is high ( approximately 35 - 40 celsius degrees), humidity in the air is low, the soil is well drained.This tree is planted in Europe ( R. Macedonia). Thank you.

Thank you for the photos. I am in conference with others that know more about diseases than I do.
I had thought perhaps it was a species of Phytophthora fungi [https://www.natlarb.com/html/phytophthora_disease.html] but you indicate the soil is well drained. I am looking at http://www.bugwood.org/fungi.html and http://www.forestryimages.org/urban.cfm and asking colleagues there what they think your tree's problem may be. Let's see what better experts may say.

Hello: I have opinions from 3 experts now .. and the consensus is that no action is necessary at this time ...but that the tree should be watched to see if something else develops. ​
Initial Detail:
a couple of them thought maybe it is sooty mold ... one saying possibly growing on insect honeydew.
Further Detail:
Sooty mold is a possibility --- that was my first thought before I saw the photos. After the photos I am not so sure. It is curious that the discoloration only appears on the tops of the branches but not on the needles which is contrary to what I would expect if aphid/scale or mealybug honeydew excrement falling by gravity from above and then sooty mold growing on the honeydew. In a couple of the photos there appear to be some dead/browned needles and needle clusters and perhaps some bronzing of needles which could be spider mites. However, to my knowledge spider mites don’t put out enough excrement to enable sooty mold growth. It appears in one photo that there may be drip irrigation. If so, it is possible that there were once aphids present to have produced sufficient quantities of honeydew to enable sooty mold growth and if there has been little to no rainfall, maybe it has not been washed off of the trunks, ...
but the drip irrigation has enabled new needle growth and if the aphids are gone, there would not be sufficient honeydew present to enable sooty mold growth!??

If there are spider mites present in sufficient quantities to cause bronzing of the needles, one should also see very fine webbing, but it is possible that the bronzing and the discoloration are the results of previous feeding and the populations have crashed or disappeared.

This is the best we can do, with a lot of speculation and without further facts or observation. If you notice any of the indicators listed in the further detail ... sugary sap (honeydew, see below) or insects and ants... or webbing indicating spider mites... then there are actions you could consider.

"“honeydew”, which is excreted by the aphids as a sweet waste product of their
sugar-rich but amino acid-poor diet of phloem sap "

Best regards,