Birch Tree Soil Deficiency

Soil pH

• Birch trees are tolerant of flooding and many type of insects. However, all birch trees require acidic soils, according to the Ohio State University Extension. Soil pH above 6.5 often leads to a nutrient deficiency known as chlorosis, which causes the leaves to yellow. Maples and birches are particularly prone to chlorosis and, in birch trees, it is almost always due to a lack of iron. The best defense against chlorosis in birch trees is to plant them far from concrete in consistently acidic organic topsoil.

Signs of Chlorosis

• The most obvious sign of chlorosis is yellow leaves. However, the color pattern varies depending on the extent of the problem and the individual tree; even the same species planted at the same site may exhibit slightly different symptoms. Scientists attribute these variations to slight genetic differences. Leaves may yellow completely or yellow only between the veins, leaving the veins green. In severe cases, leaves may scorch along the margins. Some trees experience severe chlorosis on an annual basis, yet maintain good growth, while others show a significant decline in vigor, leaving the tree vulnerable to parasitic infections.

Treating Chlorosis

• There is no practical solution for chlorosis once it occurs. Iron chelate foliar applications can provide temporary relief. However -- especially for a large tree -- this can be impractical and expensive. North Dakota State University says landscapers have reported mixed results with micronutrient capsules implanted in the trunk of a tree with chlorosis. When it works, it can provide several seasons of relief. When it does not, the results are disappointingly ineffective. The best bet is to try and change the soil pH. Apply 10 lbs. of sulfur for every 100 square feet of soil around the root zone.

Moisture Deficiency

• While some birches, like the river birch, are relatively drought tolerant, most birches will begin to decline if there is a moisture deficiency in the soil. Birches require consistent water primarily because they have diffuse porous wood and relatively small vessel cells in the sapwood. This leads to a high water flow resistance and a slow rate of water flow in the stems. Birches also have shallow root systems -- which dry out more quickly than deep root systems. In response to a deficiency of moisture in the soil, birches will drop their leaves during drought to decrease water loss.