It looks like it might have gotten burnt foliage from a heat wave, from what I can see in the photos. The newest foliage that is more vertical seems entirely unaffected, and the flatter leaves at the tips seem to be the ones that got crispy. I'd suggest mulching around the base of the plant to retain moisture, trim off the burnt parts to better track if this is getting worse or was a one time event, and when you water, it is probably better to water for at least 5 to 10 minutes with spray irrigation and not do this every day unless necessary to get new plants established. Cordyline australis cultivars should actually be pretty drought tolerant and get by with just once a week deep soaks even in 100 degree weather, if the soil is well mulched. On the other hand, this is a species that comes from New Zealand where it seldom gets to be 100F for weeks at a time, so it could just be the heat. If this continues to happen every summer, even as the plant becomes deeper rooted, this would seem to indicate that in your climate with your summer heat, it would prefer some dappled shade at the hottest time of the day, rather than full sun. The green leafed Cordyline australis species is certainly much hardier/resistant to sunburning, the newer colored forms are more prone to sun damage with high heat.

I realize technically this is not a house plant but grown almost the same way. These were both 1.5 -2 feet from the wall. Red star has some cold damage and lost it's centre spike. Meanwhile the green is just fine. They are both supposed to be zone 9 from what I read. Anyone experience this? The temperature got down to 34-36F for a few hours last week.

if dead.. things rot .. and eventually it can be easily pulled out.. whats your hurry No "hurry", per se, other than the aesthetics of it this or next year. I liked the look of the mandevilla with it, but I don't have any this year so I probably won't do that again until next year. I was also concerned that the roots of the mandevilla could be wrapped around the roots of the cordyline, and its rotting could lead to killing the other. If that's not an issue, though, then I'll just cut the old stalk down and let it do its thing :-)

Did you plant it there recently or has it been there for a year or more? It looks like sun burn to me but without more information it is hard to make a good call. I would cut part of the damaged leaves off or even cut the entire damaged leaves off. It won't hurt leaving them alone either, even though they are just a bit unsightly.