Tree careTree diseasesChlorosis on Tree Leaves

As New Leaves Emerge, Remember Chlorosis

With spring in full force, deciduous trees have been busy regaining their leaves, reemerging from their dormancy. It’s a process that never fails to amaze me. No matter how many years pass, it’s always a wondrous feeling to watch barren branches renew their vitality.

But as our trees are busy growing new leaves, we should take a minute to remind ourselves: leaves are a very important indicator of the health of the tree. Leaves paling in color are the tree’s way of telling us that something is amiss. Much like we pay attention to the body language of our pets when they are in distress (a panting tongue, a lowered tail) we must be mindful of the color and condition of our tree’s leaves. 

Chlorosis in Trees

The technical term for the unnatural yellowing of leaves is ‘chlorosis.’ It is caused by a nutrient deficiency, typically of iron or manganese, both of which are critical to the tree’s ability to produce chlorophyll. 

Of course, chlorophyll is the pigment that gives leaves their green hue, so chlorosis certainly isn’t great for the aesthetics of the tree. But the ailment may have far greater consequences if left untreated. Without sufficient chlorophyll levels, your tree’s leaves will experience reduced levels of photosynthesis and may fall into serious decline. 

Indeed, chlorosis is one most common causes of tree decline in the midwest, particularly the St. Louis area. The reason for this is the soil composition common in that region. Soils that contain lime and are alkaline in acidity (pH > 7) experience chemical reactions that make iron in the soil solid and unavailable to plants for absorption. If you know your region to have soil compositions like this, keep your eyes peeled for signs of chlorosis. 

Chlorosis may also be caused by plastic sheet mulching, water-saturated conditions, and compaction. All of these conditions limit the soil’s exposure to fresh air, which results in low soil mineral content. 

Pay Attention To Your Tree

As you admire your tree’s leaves this spring and summer, make it a habit to look for signs of chlorosis. The condition can appear as leaves that begin to yellow or simply fade to a pale green. 

However, chlorosis looks noticeably different than a leaf yellowing in the fall or a young, pale green leaf. That’s because the change in color occurs interveinally. In other words, discoloration due to chlorosis occurs between the veins while the vibrant green hue will remain near the veins. Typically, other kinds of leaf discolorations happen uniformly throughout the leaf. This particular pattern of discoloration serves as the biggest hint that your tree has chlorosis. 

If you notice signs of chlorosis, soil conditions will need to change in order to restore your tree to good health. Luckily, many certified arborists offer a solution. Mineral trunk injections are what they sound like – a penetrative method to get a mineral-rich solution into the uptake-systems of the plant. 

Before performing a trunk injection, however, it’s necessary to determine the exact amount of iron or manganese that your tree requires. Too much can be toxic to your tree. But when done properly, trunk injections can improve your tree’s condition in two to four weeks. 

Like any ailment, it’s easiest to treat chlorosis if caught early. That’s why we recommend using the spring time to not only admire your tree’s new leaves, but to get in the habit of “checking in” with them, so to speak. 

Being mindful of signs of chlorosis will minimize any tree decline that may arise as a result. The joy that many of us feel at seeing new spring leaves is a wonderful feeling – and by being attentive to our leaves, we can ensure that they stay healthy all season long. 

For help treating a tree that is suffering from chlorosis, ask us about our chlorosis treatment service. We’re happy to help!