These pictures have been taken in one of the orchards of Sanandaj, Iran, last summer. Only one tree of ‘Gala’ cultivar had showed this trait. Why did this happen?
ofoks like a stain caused by the
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Could they be infected by some kind of disease? Need more analysis for reasons. Attached is an apple which is infected and discolored by powdery mildew [from website].
It could be a viral disease? The appearance of apples in very similar to that produced by the Virus "plum pox" or Sharka virus disease in peach fruit.
Thank you all, it couldn't be a disease because only one tree showed this symptom on all of its fruits and the leaves hadn't any symptom. How about a scion x rootstock effect ?
1. Is this tree the only scion x rootstock grafting plant?
2. It can also be caused by other genetic mechanisms, such as the jumping of 'transposon elements'. Variegated flower colors were observed because the transposons jumped on the pigment genes (see attached figure). [ http://www.nibb.ac.jp/annual_report/1997/21.html ]
Thanks Dr.Yuan-Yeu Yau, I 've heard that MM106 was used as rootstock for all of apple trees in that orchard but this probability is exist that one of them has the different rootstock. I'm not sure for that and as you mentioned we need more analysis for reasons.
Regards
This can not be a rootstock influence. It seems to me that apart from discoloration, fruits surface is uneven.
These symptoms are similar to symptoms we observed on trees where fireblight (Erwinia amylovora) infected roostock, but I hope this is not a reason.
Other possible reason could be some virus ore viroid. It could easily be apple dimple fruit viroid (ADFVd).
Regards
Dear Dr. Nenad Magazin, thank you for your reply. Yes it could be a fireblight infection or ADFVd. I'm going to take samples for inspecting the reason of this trait.
Best regards
This variety is very sensitive to russet. If this tree was the first tree in the spray sequence then this is a possible explanation. Contaminated spray equipment, for example the merest trace of azoxystrobin will cause russeting.
The symptoms look a bit like viroid diseases such as Apple scar skin viroid, Apple fruit crinkle viroid, or Apple dimple fruit viroid.
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