White foam patches??
Can anyone advise what this is which we’re finding on a few plants?
That is known as 'Cuckoo spit' and is a protective foam exuded by 'Froghopper' insects:
They don't cause any significant damage.
A trowel in the hand is worth a thousand lost under a bush.
Central Norfolk UK
What we called Cuckoo Spit as children. Inside youll find an immature frog hopper insect.
Lots of info here
Nothing to worry about providing it’s not on a recently imported plant.
“I am not lost, for I know where I am. But however, where I am may be lost.”
Winnie the Pooh