White Oak Tree Response to Lawn-Related Cultural Changes? - Ask Extension
Regarding white oak trees that have grown up in a lawn area for 50+ years and have been irrigated and fertilized as such (to maximize lawn growth), ho...
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White Oak Tree Response to Lawn-Related Cultural Changes? #858066
Asked January 29, 2024, 3:35 PM EST
Regarding white oak trees that have grown up in a lawn area for 50+ years and have been irrigated and fertilized as such (to maximize lawn growth), how would they respond to a sudden stoppage of both irrigation (especially during the summer months) and fertilization for the foreseeable future? More specifically, how would white oak trees infected with Armillaria respond, and would they respond any differently than a healthy tree would? Thanks in advance!
Multnomah County Oregon
Expert Response
The oak tree's response to changes in irrigation and fertilization will depend on soil and climate conditions as well as the specific irrigation and fertilization regime that has been applied. So it is hard to predict.
In general, if the trees have a lot of lush foliage in response to previous practices and they experience serious drought in the next few years, we might expect some adjustment in the amount of foliage they can support with their root system. If the deeper soil quality is good, with high water-holding capacity and fair nutrition, then the trees can be expected to do pretty well after some period of adjustment. If the underlying soils are poor, with low water-holding capacity, then the cessation of irrigation could cause more serious adjustment or top dieback.
If these are native Oregon white oak, they are well adapted to summer drought and native soil conditions, so in the absence of disease or insect problems, they should do OK after some adjustment. Irrigation can exacerbate root disease problems, so that may have been a contributing factor for the Armillaria that is present. On the other hand, if trees are already infected with Armillaria root disease, the stress from cessation of irrigation along with summer drought could allow the disease to advance more rapidly.
In general, if the trees have a lot of lush foliage in response to previous practices and they experience serious drought in the next few years, we might expect some adjustment in the amount of foliage they can support with their root system. If the deeper soil quality is good, with high water-holding capacity and fair nutrition, then the trees can be expected to do pretty well after some period of adjustment. If the underlying soils are poor, with low water-holding capacity, then the cessation of irrigation could cause more serious adjustment or top dieback.
If these are native Oregon white oak, they are well adapted to summer drought and native soil conditions, so in the absence of disease or insect problems, they should do OK after some adjustment. Irrigation can exacerbate root disease problems, so that may have been a contributing factor for the Armillaria that is present. On the other hand, if trees are already infected with Armillaria root disease, the stress from cessation of irrigation along with summer drought could allow the disease to advance more rapidly.
