I think "yoda's" above comment should be put into an answer, seeing as he has firsthand experience (IMHO).
I know for a fact, via listening to "Gardening Naturally with John Dromgoole" weekly podcast, that Texas has had an exceptionally brutal summer this year:
Summer heat started really early in the year.
Virtually zero rain fall (except for the odd very lucky area).
Record number of days (not continuously) over 100°F (38°C).
Those above factors have put a lot! of stress on tress, even affecting fully grown mature ones...
Is the reason why Arborist Don Gardner put together and released his "Watering Guidelines" for tress this year:
I believe what you're seeing (and have heard Don Gardner say the exact same thing only a couple of weeks ago), "leaves on my peach tree turn an orange-green shade" is in direct response to the weather conditions you've been experiencing in Texas, and is a natural survival mode that the tree has gone into ie
- Tree starting to lose its leaves early than normal, so it can concentrate all its energy on surviving.
Just in the past week here in Missouri I've started to notice tree leaves (even on mature tress) browning, changing colour and falling off. Missouri has experienced a very! hot and dry July and August, more so than normal.
If the tree isn't mulched, I would:
- Put down a 2inch (50mm) layer of compost, starting about 4inches (100mm) away from the trunk and work outward as far as you can (is practical to-do-so).
- Follow Don Gardner's "Watering Guidelines".
I highly recommend you listen to, "You Bet Your Garden" podcast -- Not So Perfect Produce, 27the August 2011 (Direct link to MP3) and start listening at 13mins:27secs in.
How to water your lawn perfectly with Guy Fipps, PhD, P.E., Director of the Irrigation Technology Center at Texas A&M University.
Ignore the above "How to water your lawn perfectly", the watering information given by Guy Fipps, PhD, P.E. is first class (IMHO) and the link to "Irrigation Technology Center" is worth its weight in water for anyone living in Texas.
Additionally you may wish to take the time (7 minutes) to listen to this podcast:
Richard Hentschel, Horticulture Educator and Retired Extension Plant Pathologist Jim Schuster discuss drought and drowning symptoms and the long term problems with annuals, perennials and woody plants. Also discuss are methods for proper watering and indicators of drought and drowining