Collie,

Try a water audit of your lawn. This is done by placing cups around the lawn in a pattern that makes sense to your needs. For a specified time(enough to make a measurable amount in the cup)run your irrigation. Measure the depth of water in each cup. You can do this with different patterns on different days to increase the degree of information. Record the information on a scaled plan of your yard. You now have a good picture of your irrigation's systems coverage. It also gives you a good idea of how long you need to water. To over water the bad areas and underwater the good area or replace heads with varying flow characteristics to match the areas. This is fine tuning an irrigation system and usually not necessary in most cases. You might research if the water pressure has been lowered for some reason recently. Your local water company will have records available for pressure readings. Large Trees with long root systems are heavy drinkers and feeders. It may not be just water causing a problem but the trees slurping up the nutrients faster than the grass. Hope this helps. Aloha

Thanks lehua13
Since the rest of the lawn looks OK, I'm thinking it may not be a matter of not getting enough water. In fact, since the sprinklers in these areas are only a half-circle, and the others circular, they would give out more water, right?

If it is the trees or shrubbery slupring up the water, will this condition get worse over time? If I water these dry areas more, will the roots of the trees move upwards over time and make it impossible to grow any grass in these areas?

Is there anything else I can do?

Thanks!

Collie,

You make good points. Make sure about the water first with just an abbreviated audit by just measuring a full circle head and a 1/2" circle head. Heads are rated for flow per a given pressure. Different brands and different series of brands give different amounts of water over time. Heads may not work as advertised also.

To work on the tree areas. Irrigate shorter times more frequently so as to not water deeply. This will help the grass more than trees over the short term. See if this makes a difference. If it does then the trees are affecting the watering. Do this with fertilizer as well. Do one thing at a time. Think of it as an experiment in order to discover what is affecting what in that area. To speed things up, have your neighbor do one thing and you do another. Tree roots will be a problem no matter what but certain trees are worse than others. Do you have to worry about the amount of water you use? You don't have a brush/tree fire hazard? People in CA remove trees a certain distance from their property line because of fire risk, others hug their trees.

Since I can't get a close look at the problem areas, it can be five things:

1. Water
2. Fertilizer/micro-nutrients
3. Insects
4. Disease
5. Wildlife(rabbits)

JMHO aloha

Thanks leuha13.

I'll try the water test next week. My neighbors don't have an irrigation system, so that won't help.

I have a service that fertilizes, so the lawn is fertilized uniformly.

It may be insects...don't know how to check for that, or disease.

I don't have rabbits...but do have squirrels. The trees drop some sort of acorn and the squirrels open them up and leave the pieces all over the lawn.

I'll do some research on the types of trees I have...I'm think perhaps that is where the problem lies.

Thanks again!