A: We were wet last fall and into the earlier winter, and your leaves have a fungal leaf spot brought on by that moisture. Fortunately, control of this problem isn’t too hard.
Number One, and on its own line because it’s super important – don’t water these plants right now. Not now, not in April, probably not until late May or early June (if then!). Established yuccas and agaves only need water when we’re in serious drought conditions, because our normal rainfall is as much or more than those plants usually need. First year plantings will need occasional watering, but far less often than other new plantings. If you’re in any doubt whether the plants need to be watered, they don’t need to be watered.
Number Two, cut off badly diseased leaves outright.
Number Three, Spray Bonide Copper Fungicide monthly this spring to prevent further spread of the fungi. Once you’ve gotten some healthy new growth and the summer’s heat moves in, you can stop spraying.