Oak Tree Diseases – Burls

warty-burlsBurls can happen on oak trees, usually white oaks. They are caused by the fungus phomopsis. Burls are large swellings on the limbs and trunk. Sometimes, they occur naturally over young buds. Truthfully, the biology of burls is not well known. They don’t always negatively affect a tree and can even add a bit of character or beauty to it.

For some reason, the cambial growth, whether it’s due to environment or infection, is hyper-stimulated. The tree’s growth hormones get disrupted when the metabolism of the tree is hijacked by some other organism like a virus, fungus or bacterium. A ball of extra bark is built. Burls can grow to a great size or they can remain rather small. The largest burls occur on Redwoods and can encircle the entire trunk.

Burls can be removed by pruning or surgery. They contort the grain of wood and are actually prized in some circles. Furniture makers love them because they can add a lot of character to their pieces. Trees can carry this tumor-like growth and still look healthy above and below the growth. Oak burls can often mill out defective burls with rot and holes. You will probably want to get rid of these.

Sometimes, people sell their burls to artists, furniture makers or wood workers for cash. However, oak burls usually need to be removed. The crown gall bacterium is responsible for many burls. It comes with a little extra DNA, called a plasmid, which infiltrates the tree’s genetics. It prompts the tree to make special amino acids and growth regulators to produce the burl. The burl is obviously the preferred habitat for the bacteria.

However, figuring out what causes a burl can be difficult. The bacteria or fungus that started it can be long gone by the time the burl is formed. Burls can occasionally be associated with dormant buds, but that doesn’t explain why they get formed. Truthfully, we can tell you if you have a burl once it’s formed and we can remove it for you. We can’t figure out what caused it and if you are going to get more of them.

Research has shown that, by doing the regular things to keep a tree healthy such as pruning, fertilizing and watering it, will prevent burls from growing. Cutting a burl off will not damage the tree. It’s like taking a benign growth or wart off your skin. Burls take a long time to form, sometimes as often as 30 – 40 years. The sooner you notice the burl, the sooner we can take action.

Give us a call at 512-341-8888 if you have a burl on your tree and want it removed. We are happy to help you.

Oak Tree Diseases – Actinopelte Leafspot

actinopelte-leafspotDuring the hot Texas summer, plants can struggle with a pool of pathogens. Tubakia dryina, also known as Actinopelte Leafspot, is a pathogen most prevalent in red oaks but it can also infect white oaks and other oak variations. This disease can endure the mild Texas winters. Overwintering spores are dispersed once the summer rolls around. The spots are generally small (2 to 5 mm in diameter). They are round and reddish-brown in color. Some have a yellowish halo that surrounds the infection site. The disease is most severe in late summer and early fall.

Those spores that get dispersed in summer occur when it’s moist and wet. Since we’ve had a lot of rain this year, you might see it popping up on your oak trees. Usually symptoms occur at the bottom of the tree or within the trunk. They are the most favorable areas for the pathogen.

Actinolpelte leafspot is known to show up on trees that are under immense stress. If a tree is low in iron, it can become susceptible to Actinopelte leafspot. The fruiting structures can spread to leaf veins where they cause the most damage. They can kill leaves. Sometimes severe defoliation occurs. Actinopelte leafspot can infect trees that have fallen off the tree as well as leaves that are still on it so you’ll want to remove both the infected leaves on the ground as well as those on the tree.

On occasion, Actinopelte leafspot can be confused with Anthracnose, which we dealt with last week. (For more information on Spot Anthracnose, visit this article.) However, the spores from this disease are rather distinctive and can be easily deciphered under a microscope. Remember, we don’t diagnose tree diseases, but if your tree is sick, we can figure out the best course of action to take.

This disease can cause extensive damage, but it is not usually fatal to the live oak. Infected leaves should be destroyed and the tree should be fertilized slightly more than normal to stimulate new, healthy growth. Check your foliage for minor element deficiency. Newly planted trees, those planted within the first three years, are more subject to attack by this disease than well-established trees.

At Austin Tree, we will help you get your tree back to good health. If your tree has a fungal disease like Actinopelte Leafspot, we will make sure to get rid of the foliage infected. We will also suggest fertilization for your trees. Please call us at 512-341-8888. Again, we don’t diagnose tree diseases but we can treat infected trees.