hi sir it is hans from himachal india i have a question regarding apple diseases. i have planted apple rootstocks mm 106 in the month of january in winter, but two month later a redish color layer(2 to 3 inch around the trunk)has been developed about two inch from the the base of the tree that is basically at the collar of the plant and it has started rotting and new shooting has been started from below the rotted part, i have a doubt that the plant is suffering from collar rot but then it is a new sapling and there is no problem of wet land. i have consulted a orhcadist he tells me that it would be problem of sunscald. could you please tell me the actual problem