Young shoots become yellowish bronze, Manganese toxicity - growth restricted. Leaves show scorched brown margins. Either soil toxicity or atmospheric pollution from sulphur or other gasses, ammonia fumes from use of a mulch of fresh horse or fowl manure. Irregular yellow lines or patterns Virus infection either in in normal green leaflets. Try to obtain healthier plants.
Older leaves fall, based in plant bear.
Inadequate light to base of plant, earlier infection with mites or diseases. Petals show pinpoint marks. Aphid infection while flowers developing. No treatment at this stage. Red flowers of very deep colour.