Irrigate

Mature trees died in the last LaNina weather pattern that delivered dry weather to the southeastern US. Portions of western US have been in drought for many years. Mature trees can benefit from irrigation in drought. Drought is an extended period of unusually dry weather over a couple growing seasons. One or two years of drought can be tolerated by many well established trees if roots can explore soil unrestricted by curbs, buildings, roads, and other root barriers (see right photo). If these root barriers exist then irrigation in the first year of drought may provide benefit (left photo).

Irrigation should be applied to the soil surface in an efficient manner designed to minimize evaporation and prevent runoff. It does not need to be applied to the foliage. About one inch of water should be enough every week or two in the hottest portion of the year until normal rainfall occurs. A subsurface application using an injection needle can be useful if soil is covered by hardscape such as asphalt or concrete, if soil is compacted, or the tree is on a slope. Do not add so much water that soil becomes and remains saturated. Click here for more.