Here in Kansas City, we see the same tree and shrub problems season after season, so we asked Jason Clarkson, our Lawn Director, to tell us what to look for in our yards this summer. Many times, if you catch problems early, you can nip them in the bud and that may be the difference between saving a plant or watching it die. At the very least, you won’t have to deal with ugly plants for a season while they recover from whatever ails them. He’s taken the most common problems and broken them down into three basic categories – insects, diseases, and environmental issues:
- Japanese Beetles
- Spider Mites
- Emerald Ash Borers
- Shot Hole Fungus
- Heat/Drought Stress
- Too Much Moisture
Tree & Shrub Insect Problems
When it comes to trees, pay close attention to your junipers and cedars, river birches, maples and oaks. In your landscape bushes, pay special attention to burning bush, hollies, and roses. Here are the tree and shrub problems to look for by plant:
1. Junipers/cedars – bagworms
Signs – If you notice sudden, dramatic changes in your evergreens – plants turn brown and needles drop, look for small brown, spindle-like bags hanging from the trees. They are made of silk, and parts of the plant’s foliage. They are usually about two inches long.
Treatment – Tree looks like it’s been deprived of water, but watering and fertilizing won’t help. Cutting the bags off the plant and disposing of them before they hatch is effective but high-maintenance. After they hatch (May or early June) and begin eating the plant, sprays are best.
2. River birches/maples/oaks – Japanese beetles
Signs – Chewed leaves have a lacey or skeletonized look and may drop off the trees. A brown halo effect may appear in the upper tree canopy.
Treatment – Japanese beetles are sluggish in the morning before the sun has warmed them. This is a good time to collect slow-moving beetles by shaking the plant over a plastic sheet and then dumping them into a bucket of warm, soapy water, where they drown. If you have a large infestation, you may want to consider grub control treatments as they start off as grubs underground.
3. Roses – Japanese beetles like roses too. (See above for signs and treatment)
4. Burning bushes/holly – spider mite infestation
Signs – 3 key signs of a spider mite infestation include:
- The easiest sign to spot is silky webs woven around leaves and stems.
- Also, look for tiny white or yellow spots on the tops of leaves or needles.
- If it is a heavy infestation, you may notice a yellow/bronze appearance in one or several areas of the tree.
Treatment – You can blast the tree or bush with a strong stream from a garden hose nozzle to physically remove most of the mites, or introduce natural predators like ladybugs, lacewings, or big-eyed bugs.
5. Ash Tree – Emerald Ash Borer
Signs – Thinning and yellowing leaves, D-shaped holes in the bark, and canopy and bark loss. Luckily, this insect only attacks/affects ash trees.
Treatment – If they are not treated, the beetle will get to the tree, if there is more than 30% death in the tree, it can’t be saved. Scientists are working to find ways to stop the beetle. It’s been proven that efforts to save trees can be improved by identifying infested trees in their first year, so it’s critical to keep an eye on your ash trees now.
Disease/Fungus Problems in Shrubs & Trees
6. Maples, oaks, Bradford pairs, crab apples – anthracnose.
Signs – When the weather stays wet for extended periods, it can cause anthracnose, a common fungal disease that results in leaf spots, cupping or curling of leaves, and early leaf drop. Because it thrives in moist conditions, during dry weather, anthracnose might even disappear, but it may return with high humidity or rain. It is not a significant threat to the health of the tree and usually doesn’t require treatment.
Treatment – Prune out dead wood and destroy the infected leaves to keep it from returning.
Crab apples and Bradford pears – rust
Because it is a type of fungus, above average precipitation makes conditions ideal for this disease. Rust is a common disease in both these types of trees.
Crab apple trees – Crab apple rust (also called cedar apple rust) is most common on apple and crabapple trees.
Signs – Yellow spots on leaves turn bright orange-red with a bright red border and small raised black dots in the center
Bradford pears – Pear leaves are infected with cedar-hawthorn rust rather than cedar-apple rust. Though it is different from cedar-apple rust, both diseases work the same and control is the same.
Signs – Yellow-orange spots on the leaves. These spots begin in the late spring on the upper surface of leaves and gradually enlarge and turn orange during the summer months.
Treatment – Luckily, rust causes mostly aesthetic damage and is considered a nuisance problem rather than a tree health problem. Control is optional and generally not recommended unless the tree experiences substantial leaf drop.
7. Roses– shot hole fungus
Shot hole disease (also called Coryneum blight) is a serious fungal disease that affects leaves, flowers, and branches of rose bushes.
Signs – Look for small red spots on leaves. These spots will grow and turn purple with a white center. Eventually, the spots drop out, leaving BB-sized holes which explains where the fungus gets its name. Severe infections will leave the plant looking tattered. Limit overhead tree watering as excess water on the foliage will promote the spread of the disease.
Treatment – Remove and destroy all infected buds, blossoms, and branches. Contaminated leaves around and beneath the tree should be removed as well.
Environmental Tree & Shrub Problems
8. River birches, maples, redbuds – heat/drought stress
Kansas City summers can get pretty hot. During extended periods of heat and drought, it’s a good idea to water your mature trees and evergreens to make sure they are getting enough moisture.
Signs – Leaves will start dropping early on trees
Treatment – Proper watering is huge with trees and shrubs so if we are in a dry spell, water them once a week with a soaker hose for over an hour.
9. Evergreens – Moisture issues
When evergreens get too much moisture, they can turn brown and look sickly.
Signs – Needles start turning brown and dropping because the root systems are too wet.
Treatment – There is no treatment other than to let things dry out naturally.
Planting Tip: If you’re planting all new shrubs, it is important to plant them at the proper level – not too deep or too low.
If you notice any of these tree and shrub problems, give us a call and one of our KC landscape experts will come out and diagnose and treat your plants. We use eco-friendly solutions so it’s safe for the environment and your family. It’s all part of our Eco-Pride system of lawn and landscape care. Call us at (913) 396-6858 and get a free quote on a lawn care program or contact us online.