Ran into a support Mao

First time I've had this since the rework. His plant damage was a little over the top. Tosses plants, then walked off. They just sat in a bush until they ran at us during a fight and also zoned us from using the bushes during the lane (or we un-willingly took the damage if we wanted to ward clear them). Eventually was able to out run them with boots, but it was still a problem all over the map. He nearly took out the ADC with two plants hidden in a bush by Baron. The ADC took no other damage but the plants. The aoe slow it applies also gave us a problem. It kind of reminded me of old teemo shrooms, except of course you can see the plants and they run at you. Anyone ran into this? Have any counter play tips? The guy said he used it because apparently it has a high win rate in Korea right now. I honestly thought the damage was a bit ridiculous, but this is just my experience from one match against Mao sup.