Cypress and arborvitae have brown leaves

Question: I have two cypress and one arborvitae planted about 5ft apart on the same line. I noticed that my two cypress and arborvitae leaves are turning brown, but only on the side facing south. All other sides the tree appears to be healthy. I waterd the trees daily during the Jun and Jul months and slowed it down in Aug since the weather wasn't as humid. I'm not sure if it's the heat that is causing the brown, or something else like fungus. I'm not sure if it's because my sprinkler is only wetting one side of the ground and not the other side. Any advice is greatly appreciated.

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied August 28, 2024, 9:36 AM EDT
response: The arborvitae pictured (especially the plant in image file ending -339) do look stressed, which is not too surprising given the challenging weather conditions of this summer and the young age of the plants, since they are still getting established. The symptoms visible appear to be due to environmental stress like heat heat and soil moisture, and do not look like a fungal infection of the foliage. While it was good to have watered them during the drought, daily watering is too often, and you want to avoid risking root rot from soil that stays too wet. Ideally, to monitor plants for watering needs, feel the soil five to six inches deep next to the root zone. If it's become somewhat dry to the touch at that depth, a thorough soaking is probably needed. If damp instead at that depth, watering can wait.  When soil becomes too wet or gets soaked too often, that reduces the amount of oxygen in soil pore spaces that roots need to stay healthy. Some plants are more tolerant of root wetness than others; arborvitae and most needled evergreens don't want to get too dry, but don't have a high tolerance for staying wet either. When watering is needed, you want to soak the soil thoroughly enough that it re-moistens the soil down to that six-inch depth again, but how much water put down, or how long to run a sprinkler to achieve that, is something you'll need to experiment with, as water pressure impacts how long to water. As a rough guideline, you might need to run an oscillating sprinkler for over an hour, or give each plant around 5 or more gallons of water with a watering can or soaker hose. If using a sprinkler, you can use a shallow dish (tuna can, anything handy) to see how long it takes to accumulate an inch of "rain." Watering in this way around once a week in hot, dry weather is usually sufficient, though heavy soils might take longer to dry out and sandier soils might need watering twice a week in the same conditions.  Other than making sure the plants aren't over-watered, and keeping lawn far enough away from the plant base so that a mower or string trimmer doesn't cut the bark (which can cause serious and untreatable damage), all you can do for now is to monitor the plants for any new or worsening symptoms. Damaged leaves (like any with brown tips) will not heal, but next spring's new growth should cover them up if the plant has healthy roots and recovers well. (No new foliage will be produced this late in the season, which is normal for these plants.)  Miri

responder: The Question Asker Replied August 29, 2024, 1:07 PM EDT
response: Thank you very much. Your explanation was very helpful.   On Wednesday, August 28, 2024 at 09:36:54 AM EDT, Ask Extension wrote:

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied August 29, 2024, 1:23 PM EDT
response: You're welcome.