A. That was a mistake in judgment by your landscaper. Homeowner irrigation systems are notorious for watering plants unevenly; plants on the same valve not receiving enough water force us to overwater other plants on the same valve. The overwatered plants are easy to see. The plants receiving just enough water are not. It’s easy to make a snap judgment and assume that everything is being over watered when it’s not.
|This is drought in an established pine tree. Notice how the crown is round before it reaches its maximum height.The canopy is rather open and you can see through it which means it doesn't have a lot of new growth to fill the voids.|
Decreasing the number of minutes on an irrigation clock when all plants were “happy” is dangerous, particularly during the summer months. Plants react quickly to a lack of water during summer months. When decreasing minutes on a clock, do it during the cooler months. Then observe how the plants react to this new irrigation schedule. Plants have a few extra days before they are damaged by a lack of water during the cooler months.
|This Siberian elm tree had massive limb die back as the result of a conversion to desert/rock landscaping, the elimination of grass and a substantial decrease in the applied water.|
For a short-term fix, buy two or three hose end sprinklers, attach them to short hoses with a splitter that feeds all the sprinklers at once from a main hose. This can be done for about $25. Connect the main hose to an inexpensive, dial-type mechanical timer at the hose bib and connect the other end to the splitter.
|Hose end sprinkler.|
Water at the base of the pine tree for a total of about one hour. This should give the water a chance to soak deep into the soil where the roots are located. If water soaks into the ground easily, apply the water all at once.
|Mechanical timer for shutting off the water automatically when turning the dial.|
If it begins to run off the surface after several minutes, sprinkle irrigate water several times with a long pause between irrigations. But the total irrigation time should be about one hour. Water the tree like this once a week for the next month. This should thoroughly wet the roots growing deeper in the soil.