Your plant could be infested with spittle bug; it produces milky white substance. It is believed not to harm the plant, but you can eliminate it by hosing/watering it off of the plant (a rain will often be enough). The bugs hide under the foam, so washing it off will reveal them to predators—ladybugs and lacywings (if there are any) who will have the spittlebugs for lunch.
Your plant could be infested with spittle bug; it produces milky white substance. It is believed not to harm the plant, but you can eliminate it by hosing/watering it off of the plant (a rain will often be enough). The bugs hide under the foam, so washing it off will reveal them to predators—ladybugs and lacywings (if there are any) who will have the spittlebugs for lunch.
We hope this helps.