They remain in seventh place in the North Premier table with four wins from their four games played but they will need to improve on this if they are to present a challenge by the end of the season.
Harrogate took the early lead with a try from Guy Corser followed by a penalty from Luke White fo 8-0.
Some pressure for Rossendale gave Lewis Allen the opportunity to open the scoring for the visitors with a penalty.
With Harrogate in control in most areas a try from Jonny corser and a White penalty allowed the Yorkshire side to in at half time 16-3 to the good.
Despite a few flurries from Rossendale the second half belonged to Harrogate. Jonny Corser went in for his second try of the afternoon with Luke Edwards in for the fourth and the bonus point.
White slotted the conversion before adding a penalty with Guy Corser also coasting in for his second and his side's fifth to finish off a very productive day for the Rudding Lane outfit.
With second in the table Lymm unable to pick up a bonus point from their 21-14 win at home to Kirkby Lonsdale, the Yorkshire side are now just five points behind in third spot.
This coming Saturday Rossendale are in fact at home to Lymm in what is going to be a crucial game for both clubs.