Shrub problems - part 3

Asked July 24, 2019, 10:31 AM EDT

I have a number of shrubs in my Takoma Park, MD yard that are struggling. Many (most) others are not. See attached pictures.

#6 - #8 - Viburnum - adjacent to other Viburnums, Oak Leaf Hydrangeas, River Birches, Spice Bush

Montgomery County Maryland shrubs viburnum abiotic issues

6 Responses

We looked at your photos. There are several species of plants that are affected. This looks like a possible root issue. You did not mention how old the plants are. You may be dealing with poor site conditions like a wet poorly drained area, too much mulch, if the plants are new were the plants root bound in their container before planting etc. Did you add a lot of organic matter to the planting holes, etc. You will have to check the drainage in these areas. See our publication on these types of problems https://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/hgic/HGIC_Pubs/TreesandShrubs...

We notice a downspout in one of the photos. Check to see that the downspout is not dumping water in the root zone. If so, divert it to the lawn area. Alleviate any soil compaction and hope for drier weather. Do not overwater the plants. Make sure mulch is no thicker than several inches and keep away from the base of the plants.
Make sure mulch is no thicker than several inches and away from the base of the shrubs.

Here is more information on the planting process and post planting care https://extension.umd.edu/hgic/topics/planting-process


Marian

We looked at the viburnum photo again. This does not look like a disease or insect issue. The problem looks environmental in nature and the leaves show some scorch. Scorch can occur due to the plant not being able to uptake water due to some root loss. There can be several reasons for this such as excess water, lack of water, root injury, change in temperatures, etc.

All you can do is prune out dead wood back to healthy tissue. Check the drainage in the area and make sure mulch is no thicker than several inches and keep away from the base of the stems. Water during dry periods.

Marian

Nothing has changed around this viburnum in years. Within 5' either side are a healthy viburnum (different spp) and oak-leaf hydrangea. Leaves have been gradually turning brown from perimeter of leaf to base over last few weeks. Branches (big/small, main/side) all scratch green, even those those don't have a single green leaf anymore.

Many woody plants have been affected by the abnormal rainfall last season. In soil that is too saturated, roots do not receive sufficient oxygen and then decline -- which leads to dieback since the plant has less of a root system to take up water.

If the viburnum branches scratch green, all you can do is monitor and look for new growth next season. This viburnum may be a weaker plant and there are individual differences in root systems and genetics.

Marian


Thanks - I'm hoping for a drier summer and fall to get things back to normal.