Disease in a tree can come in many forms, often spreading from the ground up. There are a wide variety of causes of tree diseases, the symptoms of which vary just as widely. You may see the roots of your tree beginning to rot due to a fungal infection, or damage done to the bark as a result of an invasion of beetles. Occasionally, you may notice the tree beginning to die from the top down, a probably result of a phenomenon known as dieback.
Dieback is defined as the gradual death of tree branches or plant shoots that spread from the tips inward to the trunk or stem. Dieback may have one cause or a variety of causes which contribute to the gradual weakening and eventual death of a previously healthy tree. The process can take years and may not be a result of any single disease, but a variety of factors. If you notice signs of dieback in your trees, you’ll need to begin an investigation to discover the causes.
The health of the soil is a major factor in the overall health of the tree. There are several ways you can check to see if your soil is healthy. The first thing you can do is simply check the soil itself. Healthy, nutrient dense soil will have lots of organisms living inside of it. There will be worms, insects, and plant growth in any given handful of soil you investigate. If you can’t seem to find any signs of life, that’s a strong indicator that your soil is not healthy.
You can also check for the porosity of the soil. Healthy soil should not be too hard, which will prevent the movement of water and oxygen. It should also not be too powdery. Healthy soil will be made of different sized crumbs that don’t immediately fall apart in your hands. This is a sign that the soil is full of the organic matter your tree needs to survive.
You can also test the pH of the soil – that is, whether it’s become too acidic to support healthy plant life – using a pH test probe. You’ll dig a hole in the soil and fill it with distilled water. Then insert the test probe into the mud you’ve created and check the reading. Do this several times in several different spots to get a complete picture of the health of your soil.
Another large factor in the dieback of trees is invasive insect species. As trees become weakened and stressed, they tend to produce more nitrogen, potassium and phosphorus than normal. As a result, the trees become more attractive to insect attackers. As the insects invade, the tree becomes more and more stressed and the amount of nutrients that attract insects increases more and more. The insects do damage to the tree, which over time will cause the tree to die.
To protect your tree from an insect attack, you should try to ensure the tree is healthy in other ways too. You should also regularly inspect the tree for any signs of an insect attack. If there are any signs of insect damage, you can apply insecticides to the tree or use traps or oil to kill insects that are already there. Insecticidal soaps and oils can be purchased from your local gardening suppliers.
Fungal diseases are another possible cause of tree dieback. There are many different types of fungal infections that can occur, threatening various species of tree. Dutch elm disease, beech bark disease, elm yellow disease and oak wilt are just a few examples of the infections that can threaten trees.
As with the above examples, prevention is the most important measure you can take to keep your tree healthy. If you see any parts of the tree that are already decaying or dead, you should remove them. Sometimes, you may have to remove an entire tree to prevent the infection spreading to other nearby trees.
Fungicides can be sprayed around the tree as well; this will help control the spread of fungi from one tree to another. Insects are a major carrier for fungi as well, so it’s a good idea to control the insect population using the methods mentioned above to keep diseases from spreading. Certain trees are also bred to be resistant to fungal attacks. If you are interested in planting new trees on your property, consider using these hardy breeds to prevent the spread of those diseases.
If dieback occurs
If you’ve taken the preventative measures we’ve mentioned above and are still noticing dieback occurring in the trees on your property, you will need to take some other measures. You can prune dead or dying branches, although this will only treat the symptom and not the cause itself. You should remove any overgrown root stock to improve the health of the soil. It’s a good idea also to plant as many local shrubs and smaller plants as you can. These will attract local birds, wasps and spiders that can serve as predators to disease-spreading insects.
As always, if you are unsure of what to do, you can contact a professional tree service to inspect your tree and advise you on what to do to halt dieback.