Are your trees healthy? How do you know? What should you look for? When should you call a professional arborist?
Just like people, trees can get sick. Limbs, leaves, roots…different trees can suffer from and even die due to a variety of bacterial and/or fungal infections.
Treating a sick tree can quickly run into hundreds of dollars. You’ve got to either treat it or have it removed and that can easily run $500 or more to have one tree cut down and removed.
Considering not treating and letting nature take its course?Think again.
A majestic old oak can easily weigh ten tons, and even a fifty-foot pine tree with a 12” diameter weighs more than a ton. Imagine that coming down on your roof, car, or pet.
Fortunately, if you catch it early, most tree diseases can be treated easily at home by just using the right professional-grade product.
Here’s what you should do to make sure your trees are healthy.
Take an afternoon to walk around your property and inspect your trees. Look at the leaves, under the leaves, the branches and limbs, the bark, the ground around each tree, since many diseases are borne through the soil and enters the tree through its roots, and then be sure to check out the roots, where possible.
In the spring and summer, inspect your trees every week or so. During these growing seasons, diseases and insects can do damage rapidly.
Here’s what you should look for:
Healthy tree: Leaves on a healthy tree will have a lot of crisp, foliage and new growth that is healthy looking and green. Leaf colors should be bright and evenly-colored.
Sick tree: Look for signs of the yellow, brown, or brown-edged leaves, and partial-eaten leaves, as these are signs of sick leaves or pests. You should also look at the undersides to see if there are any signs of white fuzz, brown spots, rusty-looking marks, discolored leaves, bugs, or if the tree is prematurely losing leaves.
Rusty colors like orange, gold, or reddish spots on the leaf surfaces often indicate fungus problems.
Yellow leaves: environmental conditions, cultural reasons, pests or disease, and even the medium in which the plant grows.
Brown edges on your leaves can be caused by stress, lack of adequate water (because roots are constricted or damaged), or even high salt content. Leaves that are turning brown are commonly suffering from “scorch” disease, which occurs when your tree uses water faster than its ability to absorb water from the soil. This often happens during the summer when it’s very hot, and hot dry winds occur, and on trees that have limited root systems. Additionally, if you’ve recently dug near your tree and damaged its roots, or placed nonporous material like cement near it, your leaves may turn brown.
Curled or partially-eaten leaves with white fuzz on the underside, tent webs, and black mold can be signs of pests and insects.
Prevention: Most of the issues tree owners face are caused by external factors like bugs and pests, drought, soil issues, type of tree, and threats in your specific area. There are proactive measures you can take to combat some of those challenges.
Professional grade products can prevent fungus growth on leaves. Get expert advice before using them, though. The best product for your situation depends on the time of year, the type of tree, the Ph balance in your local area, soil, etc. What might work for one tree in Oregon might not work as well in Florida.
Other products can also stop rust in its tracks IF you act quickly before it spreads to your entire stand of trees. Practice good forestry techniques by spacing your plants properly to encourage good air circulation and avoid wetting the leaves when watering them.
Examples (Pictures and regions)
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Branches and Tree Base
Healthy tree: It’s pretty easy to spot healthy branches and stems, and a healthy tree base – they will be firm to the touch, the color will look normal, and you won’t see holes (bored by pests) or mold on the limbs. The site of a healthy tree will make you want to grab a chair, sit under the shade of that tree, and spend the afternoon enjoying a good book. An unhealthy tree…not so much.
Sick tree: If you see tree limbs/branches/stems swell; get knots; show signs of rot and/or decay, webbing, moss, mold or fungi; show a cracked or split surface; or display any type of malformation, chances are you’ve got a sick tree!
Diagnosing a problem with branches is complicated and influenced by many factors. What time of year is it? Is it unseasonably hot or cold? Perhaps you planted that fruit tree in the wrong season, and it just needs a bit more time to adapt. Maybe you’ve planted the wrong tree for your region, or perhaps you just didn’t water it enough during those hot months. There are a lot of variables that apply when determining if a tree is sick, how are they sick, and what to do to make them better.
Prevention: Depending on the disease or issue, you can prevent some diseases from developing, with some common sense prevention practices. As usual, the type of prevention you choose depends on the area in which you live, your soil, the type of tree (fruit, maple, oak, flowering or other type of tree?) and the time of year.
Healthy tree: Most healthy trees will lose their bark over time – it’s perfectly normal. Usually as long as you can see new bark growth under the old, your tree should be fine. Additionally, animals might pull strips of bark off a tree, or even chunks at a time. Bark often falls off due to extreme weather (real hot or real cold/snow), so if you notice it’s coming off around those times, then again, your tree is most likely just fine.
Sick tree: A sick tree might show signs of wilting bark, bark strips on the ground, termites present in the bark, and blister bark or cankers, weeping sap, and mold.
Prevention: Just like with leaves or your tree base/limbs, numerous influences could affect the health of your tree, so the best prevention is to keep an eye on your tree and the bark. Early intervention is critical to prevent diseases from spreading and widespread damage to your trees.
For instance, if you live in coastal Southern Californian, be on the look out for weird black growths on the trunk of your oak trees. Those are called cankers, and cankers are primary symptom of a pathogen known as Sudden Oak Death. It’s highly contagious and if you’ve got Sudden Oak Death pathogen on one tree, all your other oak trees are at risk, as well as a few other species. If you think you might have Sudden Oak Death on your trees, snap a picture and post it here.
Mushrooms around base or under canopy
Healthy tree: No mushrooms or other fungi on the tree, around the base, or under the canopy. Mushrooms and conks indicate potential decay inside the tree. More than 80% of all tree failures are related to rot around the root crown due to decay.
Don’t limit your inspection to just under the canopy. Tree roots can extend up to 2.5 times the radius of the drip line or equal to the height of the tree and mushrooms anywhere within that range can be a sign of problems.
Sick tree: Fungi usually attack oak trees, but they will grow on other types of trees as well. Most fungi can be controlled, but the fungi of all mushrooms that is almost a death sentence for your oak tree is the honey fungus. It’s called the honey fungus, because it smells like sweet honey. There’s nothing sweet about this fungus, however, as it attacks the root of an oak tree, decays the roots, and can eventually kill them, if left untreated.
Mushrooms growing further out from the base of the tree can be a sign that the tree’s roots are rotting. The roots on some trees can extend out a distance equal to the height of the tree and what might seem like an innocuous patch of mushrooms may be much more ominous. If you’re mowing in the area around the trees, be particularly alert for the presence of mushrooms, and if you don’t do your own mowing, ask your lawn care people to watch for them.
Prevention: it’s important to talk to a professional arborist immediately. Some fungi spread underground, especially the honey fungus, and can quick attack other trees in your yard. Professional-grade products are effective, but you need to act quickly before any fungi spreads. Examples (Pictures and regions)
Now that you understand the basics of inspecting your trees, let’s talk some common diseases and the symptoms of each.
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Common Tree Diseases
Oak Wilt (Ceratocystis fagacearum)
Oak Wilt occurs in 24 states in the eastern United States and is not known to occur elsewhere. It can affect all oaks, and while it is a minor problem for white oaks, it can and has killed millions of red oaks nationwide,
Sudden oak death (Phytophthora ramorum)
Found primarily in California and Oregon, where it has had devastating effects on oak trees and other plants, sudden oak death is a tree disease caused by a fungus-like plant pathogen. The pathogen also infects rhododendrons, camellias, and other common horticultural plants, causing ramorum blight.
Sudden oak death symptoms mimic several other diseases and pests, so this disease is particularly hard to diagnose, and it’s critical to start treatment immediately.
Pyhytophera (several varieties):
Pyhytophera is a type of invasive root-rot. It was the cause of the Great Irish Potato famine in the 1800. Today, it affects all varieties of trees.
Anthracnose is a fungus that destroys trees and other plants. The signs mimic other diseases that are similar, so diagnosis can be challenging. You should look the underside of your tree’s leaves for a number of small tan to brown dots, about the size of a pin head. See any of those, and chances are you might have anthracnose. .
Needle blights (Dothistrama, others): You’ll know you have needle blight on your pines if you start to see deep-green bands and yellow and tan spots on the needles. These colors quickly turn brown to reddish brown during the summer months, and may even be brighter if you live on the West Coast. The infection is most severe in the lower crown area of the branches.
While treatment won’t cure the tree immediately, nor will it save the currently-affected needles, this process will eventually allow new, undamaged needles and branch tips to replace the diseased ones. Only use top rated professional products. The wrong product is simply a waste of time and money and can cause other problems.
Dutch Elm disease
Dutch Elm Disease (DED) is cause by a type of sac fungi that is spread by elm bark beetles. This virulent disease is believed to have started in Asia, spread through Europe, North America, and New Zealand, and is difficult to control.
If you find the upper branches of your tree showing leaves that have started to wither and yellow in summer, months before the normal autumnal leaf shedding, this can be the first sign of DED. Eventually, the disease will spread, and the branches and roots will die – killing your tree.
Initially the only way to control the spread of this disease was to cut and burn all the trees affected. Eventually a vaccine for trees was created, but now this disease has started to develop and the once-effective vaccines are not working as well, and are showing resistance to the vaccines. If you suspect your tree has DED, you should get it diagnosed immediately, and seek treatment by an experienced arborist.
You know the old saying: an ounce of prevention is worth a pound of cure. That’s as true for the health of your trees as it is for everything in life. Here are a few ways you can help prevent disease from taking root in your trees.
Practice good forestry techniques
Start with a good, solid plan and professional advice. Then use the treatments that professionals use, not just what a salesperson at the local hardware store recommends.
Don’t build nonporous structures too near your trees. Patios, driveways, and concrete porches can all damage roots or cause them to overheat.S
Watch for signs of stress in your trees and check the leaves, branches, canopy and ground around your trees. Early detection is critical to saving trees and preventing serious damage to your home and other structures.
Consider a preventive spray program for your trees, especially for fruit trees. Make SURE you consult a professional arborist first. Modern formulas are systemic. They’re sprayed on the trunk or ground and are absorbed into the tree and transported to every inch of it. Do NOT use system treatments on fruit trees, since the chemicals will be absorb by the fruit
Water your tree during a drought, but don’t overwater it; your tree might be used to going without water, so if you begin giving it too much, you could make it sick!
During a drought, DO water your trees regularly. Water the base of the tree and try to keep from watering the whole plant and the leaves. Keep the area around your roots clean and free of debris.
Maintain good soil by applying a good organic mulch around the base every year or so. Great soul helps make the tree more resistant naturally to insects and disease. Fertilizing is an option, but each species of tree has different requirements and all products are not suitable for all trees. Consult a professional arborist before supplementing Mother Nature. Good organic mulch should always be your first choice.
Keep the area around your trees clear of debris and weeds, and make sure there is proper drainage for the roots so that nutrients can be absorbed efficiently.
Trim, prune or remove trees to increase air circulation and sunlight exposure.
Natural Insect prevention
Ladybugs, Lacewings, and Praying Mantis’ are fantastic at controlling and preventing bug and pest infestation.
Ladybugs will eat up to 50 to 60 aphids per day, and while aphids are their favorite meal, they’ll also consume a variety of other insects and larvae including scales, mealy bugs, leaf hoppers, mites, and various types of soft-bodied insects.
Lacewing adults hibernate in the winter months, but lay eggs in preparation for the beginning of spring; that’s when their larvae hatch! Green lacewing larvae have voracious appetites, and can eat up to 200 aphids and other garden and tree pests per week. They just suck the juice right out of those pests and keep your trees clear of bugs!
The Praying Mantis blends well into most gardens, due to its odd, spiny body and green coloring. They love eating other bugs and insects, and starting chowing down almost immediately after birth, however…they aren’t very discriminate! So if you release ladybugs, lacewings and praying mantis’ into your garden – you may find the praying mantis will win the war.
Treating and preventing tree diseases is far more complicated than you’d think and yet extremely cost-effective. Make a plan to inspect your trees regularly for early signs of disease. Symptoms vary based on the type of tree, the time of year, soil conditions, the area in which you live and so many other factors that it’s often difficult for the weekend gardener to accurately diagnose and treat problems.
The faster you get expert advice and professional grade treatment, the happier you’ll be with the results.
If you’d like to schedule an online consultation, give me a call at 509-270-5575.