This is a fungal disease that causes older leaves to curl and new leaves to be malformed and discolored. If a tree is known to be infected (if it showed signs the previous year), continuation of the disease can often be prevented during the dormant season with horticultural oils. See also fungus.
                                                            
                                                     
                        
                                                
                        
                        
                            leaf malformation indicative of over watering, over-fertilizing, lack of magnesium, insect damage, fungus damage or negative tropism
                                                            
                                                     
                        
                                                
                        
                        
                            Leaf malformation due to over watering, over fertilization, lack of magnesium, insect or fungus damage or negative tropism.