Cause Periodic episodes of cold weather (including frost events) during flower stem elongation can result in yellow banding of the flower stem and leaves. The alternating temperatures slow or speed up flower stem elongation.
Reference Hanks, G. R. and Chastagner, G. A. 2017. Diseases of Daffodil (Narcissus). In McGovern, R.J. and Elmer, W. H. (eds.) Handbook of Florists' Crops Diseases. Springer Int.