why are the leaves on my cucumber plant getting a white mould lke residue on them? They are still producing excellent cucumbers. they are in my greenhouse.
This sounds very much like powdery millddew.
Keep the groud from drying-out around the roots ( not as easy as it sounds, I know!) and treat the leaves with a fugicde, check previous questions for further details,its a common problem of late. Good Luck Tbird+