Grass & Pine Tree Issue

Asked May 11, 2020, 11:41 AM EDT

Hello. Need help with two issues.
1.We have yard treated throughout year (too include grub control). I noticed some brown patches (see picture) throughout lawn. We also have lots of dear that go thru property. Q. Any idea what is causing brown spots and action to take?

2. Back edge of our property is lined with Pine Trees (they are about 24 years old). One of the Pine Trees (2nd from right) has turned brown all the way down (see picture). There is a neighbor's house beyond trees. Q. Is tree dead? What do you think we should do to tree, if anything? Lastly, all of the Pine Trees limbs touch ground now - should we cut the limbs off at bottom? THANKS.


Carroll County Maryland

1 Response

The bare spots in the lawn could be caused by a number of potential issues. Grub populations typically cause turf roots to detach and the sod can be pulled-up a bit like a carpet; this does not appear to be the case here, though grub presence would depend on how effective the lawn service treatments are. Dead seasonal grassy weeds can create patches of brown blades like this; infected turf can also lose foliage in patches, especially in wet weather. This is the header page for an array of information on lawn care and issues: https://extension.umd.edu/hgic/topics/lawns. Since we cannot easily narrow-down the causal agent from the photograph, you can compare the information on turf diseases and weeds to see if they seem to match your symptoms (under "lawn problems" and "lawn weed ID and management"). If you wish to overseed the bare spots, you can look into the "lawn renovation and overseeding" section, though perhaps your lawn-care company offers this service.

It may help to have a soil test performed on your lawn soil if one has not been done in the past three years. This will let you and the lawn-care company know if fertilization is needed (such as with control of the disease red thread) or if over-application of some nutrients is occurring. Information on soil testing and a link to area labs can be found here: https://extension.umd.edu/hgic/topics/soil-testing. (Note: current conditions have temporarily closed UMass' lab, though others seem to be operating normally or with slight delays.)

We cannot determine the cause of death for the pine tree from the photo, but here too there could be multiple potential causes. Eastern White Pine (Pinus strobus), which is what these trees appear to be, are commonly sold and planted in suburbia as fast-growing evergreen screens. However, they are best suited to cooler summers and more sharply-drained soil than we have in central MD. In the wild, they occur only in Western MD, though they are planted and naturalized in much of the piedmont. Our hot summers (especially overnight temps) combined with often poorly-drainaing, compacted clay-based soils, can cause them stress. They are also not well-adapted to extremes of wet or dry soils; the past two years, for instance, saw both weather patterns occur over the course of the year. Stressed trees that were not irrigated during a drought could have suffered root damage and been more prone to attack from insects and pathogens.

The dead tree should be removed, at the least as a safety measure before it falls as it deteriorates over time. Given how closely the plants are spaced, a replacement is not recommended, as the trees are not yet mature and will fill-in this gap on their own. Many pines naturally lose their lowest branches with age; they gradually defoliate and die back. You can prune off these in winter if you wish to open-up the base of the trees, but they will develop bare bases in time regardless. There is no risk to the health of the tree in having low-hanging branches. On many conifers such as pine, removal of live branches with foliage will not result in re-growth or replacement of that foliage or branch in that location; the bare zone created will remain so. This may be desirable in the case of removing branches in the way of paths or gardening work, but could be undesirable if that foliage was useful in screening a view.

If you wish to limb-up the trees (the process of pruning off lower branches), you can follow the guidelines here on how to cut the branches safely: https://extension.umd.edu/hgic/topics/pruning-trees. See the diagram under "proper pruning cuts" around the halfway point of the article.

Miri