|I live in Phoenix and have an agave plant in my yard which was always doing quite well - it still looks healthy (ie; good color, new growth, no rotting or holes), but it's closed up almost entirely - not sure if it's a weird reaction to summer heat or to over-watering??
|You may want to open and check the inside of the plant leaves for signs of scale damage living under the newly forming leaves in the center. If so, purchase an insecticidal application from Home Depot. It's also important to note that many varieties of agave live only about 10 years and it may be at the end of its life cycle. Wish I had better news but I'm not sure what else it could be. You can also check with your local Master Gardner's for further information or local extension office on this. Good Luck!