To cite daymetr in publications use:

Hufkens et al. (2018). An integrated phenology modelling framework in R: modelling vegetation phenology with phenor Methods in Ecology & Evolution, 9(2), 1-10.

Corresponding BibTeX entry:

  @Article{,
    title = {An integrated phenology modelling framework in R:
      modelling vegetation phenology with {phenor}},
    author = {Koen Hufkens and David Basler and Tom Milliman and Eli K.
      Melaas and Andrew D. Richardson},
    journal = {Methods in Ecology & Evolution},
    year = {2018},
    volume = {9},
    pages = {1-10},
    url =
      {http://onlinelibrary.wiley.com/doi/10.1111/2041-210X.12970/full},
  }