Does anyone have any idea what the frothy substance that sometimes appears on chrysanthemum? I assume this is a pest or disease of some sort. Any ideas?
Yes this is a pest, the froghopper to be exact. It creates and lives in the frothy substance you describe, which is called 'cuckoo-spit'. It sucks the sap and distorts growth. To get rid of it first hose down the plant with water and then spray with Hexyl.
