Based on the picture, it's leafy gall disease caused by Rhodococcus fascians, but needs a pathgenecity and molecular assay to be sure
Sometimes limb flattening of apple is caused by ringspot virus which is transmitted by dagger nematode.
The pattern of growth displayed in the photograph is commonly called crestose (a crest). Many factors can result in cristate growth. This includes pathogens of various types as well as agricultural chemicals. Growth of this nature can be induced by exposure to agro-chemicals such as pre-emergents, herbicides, and synthetic growth regulators (which may be utilized as herbicides e.g. 2,4 D or for manipulation of flowering/fruiting). As suggested above it would likely require a pathology assay. If the condition appears to be transmissible and does not appear in corrolation with the use of agricultural chemicals it would most likely be due to a pathogen of some nature. Many pathogens can directly alter a plants physiology via growth regulators.
The sympoms on apple you showed are called fasciation
The cause has to be diagnosed: it could be a genetic mutation, a phytoplasma or a mite In some cases the bacterium Rhodococcus fascians has been involved. Alteration of hormonal balance is the physiological alteration associated to this symptom.
I am pretty sure that is not a virus, having completed a PhD on sap-transmitted viruses of Prunus which are similar diseases to those affecting Malus. Also, prunus necrotic ringspot virus would not cause a symptom like that. My guess would be hormonal weedkiller damage. Easy to rule out- find out what weedkillers the grower uses.
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