I had my yard landscaped this summer, and I got a nice Chilean Mesquite and a decent size palo verde tree put in, my first time having either of those. Both of them looked great for months, but in the last couple weeks, my palo verde's leaves are turning brown and falling off. Not all of them, but it's becoming a fair amount (maybe 25%?). I'm wondering if this is normal for this time of year, or is there something I should be doing about it? I've decreased the watering from the drip system since it's now cooler. Thanks for your help.