My Newly Planted Red Oak Leaves Are Turning Brown


The foliage of the red oak, also known as Quercus rubra, is recognised for its beauty and the tree’s towering, rounded canopy. Hardy in plant hardiness zones 4 through 8 as designated by the United States Department of Agriculture, in general, this tree is a hardy species. However, the majority of trees are vulnerable when they are initially planted, which is within the first three years after they are placed in the ground. This is the amount of time it takes for them to get established.

Watering Problems and Drought Stress

The majority of tree species, including the red oak, are prone to having their leaves scorched. This happens when the tree does not have enough moisture and is unable to take in enough via its roots to compensate for the amount of moisture that it loses through its leaves. It’s possible that leaves will first turn yellow, then brown, and finally fall from the tree. This may happen when there is a lot of heat in the summer as well as when there is a lot of dry cold in the winter. According to Davey Tree, leaf browning in oak species may also be caused by the stress of dryness.

You may combat these issues by supplying enough moisture throughout the summertime. The recommended amount is an inch of water each week, which should be applied in the form of a single, in-depth soaking rather than repeated sessions with a sprinkler. Always check the trees’ moisture levels in the winter to ensure they have enough hydration before a frost is expected.

Environmental and Cultural Issues

Trees that have just been planted and show indications of stress may be suffering from a condition called transplant shock. They lose the majority of their root system when they are dug up from the nursery, and it takes several years for them to grow back. As a result, the tree frequently reacts by developing a wilting or browning crown as a result of its inability to take in enough water to keep its foliage adequately hydrated.

Mulching the area surrounding the tree and watering it one inch deep once a week during the active growth season are both helpful. Oaks are also vulnerable to harm by salt, which may cause the margins of the leaves to become brown and the whole leaf to turn brown. They are not appropriate for gardens in areas where there is a risk of being hit by ocean spray or where seawater gathers and flows through the garden.

Damaging Oak Diseases

Oak wilt, as stated by the Missouri Botanical Garden, results in the browning and eventual death of oak leaves within one to three months. You will have to cut down the tree in order to prevent the illness from spreading to any other red oaks since there is nothing else you can do to rescue it.

Oak anthracnose, which similarly forms blotchy brown areas on leaves, is another possible reason for the browning of oak leaves. The best treatment for this illness is to assist your tree get established as early as possible by providing it with sufficient water so that it can survive the ailment. It is best to refrain from trimming oaks during the months of April and June since this is the time of year when illnesses are most likely to spread from sick trees or insects that transmit such diseases.

Oak Species Pests

Even while only a small number of insects, such as leaf miners, are responsible for the browning of oak leaves, foliar browning may still be caused by insects. If you remove one of the browned leaves and tear it apart, you should be able to identify whether or not the damage was caused by leaf miners. The top should come apart from the bottom, and there should be particles of faeces in between.

Raking and clearing away trash from beneath the tree on a regular basis is the most effective tactic for preventing the spread of the insects and eliminating their pupal stages. It’s possible that other insects, such aphids, may cause leaf deformation, although dealing with them often isn’t necessary.