The reigning YPLN Premier champions have now lost three of their five matches in 2022 with their latest defeat coming by a big nine-wicket margin.
Put in by home captain Piet Rinke, they were soon in trouble at 26-3.
Luke Edwards (30) and captain David Wainwright began a recovery, but when the former was out they were still struggling to put a big score together with more wickets falling to leave Cas on 64-5.
Wainwright continued to battle at one end until spinner Ben Elvidge claimed his vital wicket after he had made a fine 57, including four fours and a six.
Although Alex Kaye contributed 23 and Eddie Morrison 19no, Castleford were all out for 162.
It looked a below par score and so it proved as Duncan Brown raced to 24 before falling with the score on 36 then Oli Stephenson came together with Breidyn Schaper for an unbroken second wicket stand of 128.
Connor Hyde took the only wicket to fall with Stephenson mixing solid defence with positive front foot drives and Schaper using his excellent footwork to thwart the visitors’ bowling attack.
Stephenson grew in confidence, utilising the pull shot to great effect, hitting two sixes into the popular bank as the opener reached his half-century. Schaper soon followed his partner in obtaining his own 50.
Stephenson finished on 65no and Schaper unbeaten on 69.
Castleford seconds also batted disappointingly as they were all out for 76 to lose by 39 runs to Carlton Towers in Division Two Ebor.
Rajdeep Halder top scored with 17, but a good effort in the field was undone as Carlton had been dismissed for 115 with Nathan Beck taking 4-42, Gopi Chemudupati 3-11 and George Gibson 2-10.