The ants might be after honeydew from aphids - does the plant have an aphid infestation? This is the most likely explanation for their climbing up the plant. If the pot is standing on a patio or paved area, then you'd be wise to raise it off the ground by using pot feet or something to give some clearance beneath. Ants sometimes do make nests in pots and whilst they don't eat the roots, they will chew through them to make more room for their nest when they need to - but they don't usually climb up the plant if that is what they're doing.

Thanks. No aphids though. There was more on the gravel though I will raise it up.

i think you have a nest in your pot in which case they can kill the plant bye as bamboo sais chewing threw roots and the very nature of having all the tunnels in the pot . just get some ant powder to kill them of and perhaps repot at the right time . as bamboo sais potsare better on feet of some sort .