How Chestnut Trees Talk to Us

There are many things a chestnut tree will tell you if you know how to listen. Chestnut trees talk in simple terms like, "I am hungry", "I am thirsty", and "I am not feeling so well". With chestnut trees we do not have "Read my lips", but "Read my leaves" and reading a leaf is what we will do.

Part of the training an Emergency Medical Technician receives is how to determine if a patient is "Sick or not sick" from just a quick look. Chestnut trees can also be treated in the same way from just a few feet away determine "Sick or not sick". The good news is a chestnut tree's sudden death is defined in weeks or months not minutes or hours. So by just walking by a chestnut tree and taking a quick look at the leaves we will be able to determine "Sick or not sick".

Chestnut trees tell us a lot of how they are feeling by their leaves and their bark. Usually, when there is a serious problem with a chestnut tree the leaves will show the first signs. As the problem gets worse, the bark on the tree will have signs telling us "I am feeling real bad, like I might die". If the bark is showing signs then it may be too late to do much to save the tree. We will take a look at both healthy trees and sick trees. Ever have someone say to you, "You are not looking so good, are you feeling sick?" Well, with chestnut trees, looking good is having vigor and good looking leaves. Generally speaking, a sick chestnut tree will not produce nuts. If your chestnut tree isn't producing nuts with kernels, then it might be stressed by the growing conditions.

So let's start with what to look for in a healthy chestnut tree. During the growing season we have both leaves and bark to examine. While dormant, only bark is present for examination and can only help us determine if the chestnut tree is very sick or dead. The picture below is of a Bisalta #3 chestnut tree at bloom time (mid July). This tree is saying "I am healthy, full of energy, and look at me grow". These traits can be visually observed in the quality and size of the male flowers (catkins), the size, color, shape of the leaves. The terminal growth, that is the new growth at the end of the branches, is more than 12 inches. Not all chestnut tree cultivars look like this so the evaluation of health should be compared with a like chestnut cultivar.



Notice the bottom of the leaf is a lighter color than the top of the leaf. The amount of difference in color varies between chestnut cultivars. On some cultivars, like this one, the color difference is slight but noticable. The next picture is of a Colossal chestnut tree. Notice the bottom of the leaf is much lighter in color than the top.



Also, take a good look at the amount of leaf curl. The Colossal chestnut leaf curls when the summer sun is intense. Other chestnut cultivars do the same leaf curl, but usually not as much as the Colossal does. In other plants when the leaf curls like this, it is a possible indication of water stress, not so with chestnut trees. When the leaf curls like in these pictures it is normal and healthy.

If we kind of just look at an overall perspective of these top two photos, we see leaves that are complete without munch marks or holes in them, the color is a consistant color across the entire leaf and each leaf on the branch looks just about the same as all the others. These are examples of what you would look for when checking the health of your chestnut trees. Next, we will look at photos of chestnut trees that do have health issues.

One of the most common condition found in chestnut orchards is nitrogen deficiency. The problem with just looking at the chestnut leaf is that some other conditions can look just about the same. Here is some examples. The picture below is of a Colossal chestnut tree deficient in nitrogen. Notice the yellowing at the ends of the smaller leafs. Difficult to notice in this photo but the size of the leafs are about 60 percent of what a healthy Colossal leaf would be.



This next picture shows a chestnut tree with boron damage. The orchardist applied a foliar spray of boron to the chestnut tree. The application exceeded what the chestnut tree could handle. The resulting damage looks like what this next picture illustrates. If you apply boron as a foliar spray then you may end of with your chestnut leafs looking like this:



In both the picutres of the nitrogen deficency and excessive boron the leaf edges have yellowing and even some browning. In a way it could be difficult to tell the difference if you did not know the history of what the chestnut tree was exposed to. This next picture is of a chestnut tree that is on its death bed. The tree has root problems that are showing up in the leaves. Since the roots are breaking down, the small leaves appear to be doing ok, but the the large leaves are brown over 50% of the leaf area. About 3 weeks after this photograph was taken the tree was dead. The culprit, in this case it was phytophthora, also known as root rot.

Next we turn our attention to the base of the chestnut tree where we find the graft on a grafted chestnut tree. Almost all plants that are propagated using grafting of a root stock and the scion wood have the potential of graft union failure. Graft union failure can show up on chestnut trees many years after the graft was formed. A failure at the graft union can have a number of different indicators such as top die back and underperforming growth observable in undersized or deformed leaves.

The picture also shows that its just not the leaves we need to be observing, we also need to be looking over the entire stucture of the tree such as the branches, the trunk, and the bark. The bark above the graft is one color and below the graft it is a different color. Aside from the bark color having differences, the size of the trunk is different sizes above and below the graft. As you can see, being able to recognize potential problems starts with coming to know what a good healthy chestnut tree should look like.

Dehydration is a problem for many living organisms, the such likes of plants, animals, and people too. Dehydration starts with a simple "I am thirsty" progressing through "Would someone just give me a drink of water", and without intervention, dehydration can result in the death of the organism. Pictured below is a chestnut tree saying, "Would someone give me some water, I feel like I might die". The reality of the situation is the chestnut tree is suffering from water stress induced by drought during the growing season. Chestnut trees are drought resistant. The tree pictured here is a Colossal that will drop all its burrs and some of its leaves because of the water stress. The tree went dormant early without producing any nuts. Rains did come before the end of the growing season providing the tree with enough water that the tree made a full recovery next growing season.

There are two important lessons presented here. The first lesson is that an orchardist needs to take time to look over the trees in the orchard, observing the leaves and looking for possible problems. The second lesson is keeping history. When a patient arrives at the doc's office, the doc asks all kinds of questions about what is happening, what happened in the recent past, and for new patients the doc asks for a complete history.

When a problem is presented to the doc, the doc will often order some lab tests. With chestnut trees our lab tests consist of leaf samples and soil samples. The results of the lab test will likely provide enough information to find a way to correct the presenting problem. If your chestnut tree orchard is facing a problem then get the lab tests done, its worth the money and cuts out a lot of guessing.

Taking time to walk through the orchard is a great stress reducer. Take the walk often, express your thanks for at least one thing you can be thankful for and your life will be a lot happier.