I’m sure that you would guess that a lot of plant problems in July/August are heat related–it’s hot–it’s dry and sometimes windy-so plants, grass and trees are having a hard time holding onto water-they need enough watering of the soil to give them a good drink every 5 -7 days in clay and 3-5 days in sand depending on your plant choices and sites.
This time of year if your sprinkler system is not watering evenly it really shows up–most of the time that is what the problem is. However many of us wrongly interrupt what we see- ( dry tan patches in the grass and crispy leaves on our plants)- as a signal to water more often–which at first seems to be the answer–if you get the areas that do receive water when the system is running over wet -the moisture soaks out into the dry areas close by-so for a while this seems to be the fix–until you wreck everything by over watering it to try to fill in the dry spots. Even if you don’t think I’m right- do the watering test to rule it out–all you have to do is put cans in the brown places and cans in the green places and turn the system on–all of the cans should fill up to 1 inch– to really water the soil well. If this test proves what I have said then tweak or get the system tweaked ( tell your sprinkler guy what you found out-and tell him that you want more water applied when the system is on in those areas that aren’t being hit) –Very often even though the top of the soil gets wet the sprinkler heads are shooting over spots and only wetting that area enough to make it appear watered ( the can test will tell all) . If you just can’t manage this then use a hose sprinkler to apply more water only where it is needed and don’t over water everything else--you will have a healthier garden and a smaller water bill.