What happened to my dogwoods (Cornus florida)? This was the question form the caller this week. I needed more information so, I did a field visit to find out.

Tree problems can be really difficult to diagnose. Often, the problem that we are noticing today began three to five years ago. While trees can handle a lot of stress, there is often a straw that breaks the Camel’s back moment when the tree just shuts down and dies. The leaves will turn brown and cling to the tree, not always but usually this is the case. In other situations, the tree will give us clues that there is an issue. The top of the tree may begin to look thin or there is lichen growing on the branches or trunk. These are indicators that there is some stress or growing problem.

In the case of the thinning at the top, this is very indicative of a root issue. The thinning or even defoliating can’t tell us what the issue is but if we pay attention to the trees in our landscapes, this can be like a distress signal from the tree telling us we better do something quick. The root issue could be root rot from too much water in the soil. It could also stem from being planted too deeply when it was young. Lastly, it could be a soil issue stemming from compaction. The tree’s roots will have difficulty growing through compacted soils, especially when it gets dry. Years like this year test a tree’s resilience.

Lichen is a neat sort-of pseudo plant, they are half algae and half fungus. Lichens can come in different shapes and sizes and colors. They are not killing your tree! These nifty little organisms can only establish on something that is nearly stationary. They will be on a fence post or even an old car that has been sitting for years. In this way, we horticulture folks can use them like indicators to tell if our plants are growing the way they should. There are a number of reasons why your tree may not be growing well. First and foremost, the tree may be mature. Trees have a somewhat predetermined size, once it is reached they slow way down. There may be another issue if the tree is young. Look for root issues or nutrition issues if this is the case. Lastly, compacted soils can again be the issue. When soils are compacted from traffic or equipment, roots cannot grow through them, this hurts the tree.

So what is the issue with the dogwood? Well, there are a number of issues to report, not the least of which is their age. In their natural setting, dogwoods have a life expectancy of around 80 years. However, dogwoods in a landscape are not in their native environment, they are most often found surrounded by turfgrass that is robbing nutrients from them. They are also usually planted in full sun situations that can lead to stress. Dogwoods in nature are an understory tree that will be found in full shade and shallow, fertile, and moist but well-drained soils. In a natural setting, the soil will be covered with leaves and decaying organic matter that acts as a mulch. This helps to moderate temperature and moisture. In a landscape situation, turfgrass can be in direct competition for nutrients, adding a mulch ring around the tree can cut down on the competition, prevent weeds, prevent mechanical damage, and provide the benefit of moderating temperature and moisture.

A major contributing factor this season is the drought that we have been experiencing, especially when coupled with the facts already mentioned. Dogwoods, along with redbuds, willows, and maples are shallow-rooted trees. This is an issue because they respond very quickly to both dry and wet conditions. During seasons when we experience drought conditions, is it important to give your trees some irrigation. What does that look like? Think about 10 gallons per inch of tree caliper at chest height. So, a three-inch diameter tree would receive 30 gallons of water. Use a shower nozzle on the hose or drip irrigation to deliver the irrigation water to the soil at the dripline of the tree. The dripline is the average area where the branches end around the tree. This is where the majority of water uptake will occur.

If you are having an issue in your home garden or landscape, send your questions to Gene Fox, Consumer Horticulture Agent with the North Carolina Cooperative Extension Service, please email Gene at gene_fox@ncsu.edu or call at (252)946-0111. You can also ask to speak to a Master Gardener! On Mondays and Wednesdays between 10:00 and 12:00, they are on the Greenline to answer all of your home horticulture questions. Check out our Facebook page, Beaufort County Master Gardeners, for The Plant of the Week and Food Garden Friday! Until then, Happy Gardening!