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Homeowner’s Guide to Dogwood Diseases and Care

Dogwood anthracnose. Dogwood borer. Powdery mildew. You may have heard these scary terms, and they may have discouraged you from planting Flowering Dogwood Trees in the past. Yes, Dogwoods have recently been under attack from some troublesome insect pests and diseases. The good news is that you can grow healthy Dogwoods with a little know-how. This guide will show you the three simple keys to growing disease- and pest-free Dogwoods in the home landscape:

• Know the symptoms of the most common Dogwood problems
• Choose healthy Trees
• Practice proper Dogwood Tree care

Dogwood problems to look out for:

Dogwood anthracnose—This fungal disease can weaken and even kill a Tree over time. The first symptoms are small leaf spots with purple halos, which may expand to form larger tan blotches. Infected leaves will cling to the Tree all winter instead of dropping in fall. Dogwood anthracnose disease may spread to the twigs, larger branches, and trunk, causing dieback. The lower branches will die first.

There are other leaf spot diseases which are merely cosmetic and cause no serious harm, so don’t assume the worst if you see a few spots. Also, Dogwood anthracnose is much more common in the wild in cool, moist forests at high altitudes than it is in the typical home landscape, so in residential areas the situation is less dire than it may seem.

Dogwood borer—This insect is the larva of a moth which burrows into a branch or trunk of a Dogwood Tree and feeds under the bark, weakening the Tree and sometimes killing it. Borers often gain entrance through a wound in the trunk, such as that caused by a lawnmower. One symptom of borers is when Dogwood Tree’s leaves start to turn red in summer. You may also see some dieback in the canopy. You may also see rough bark and frass (caterpillar droppings) at the point of entry, too.

Powdery mildew—This fungal disease appears as a white coating on Dogwood leaves and buds, particularly on newer growth. In a heavy infestation, the leaves emerge distorted. Powdery mildew isn’t a particularly serious disease, and the damage is mostly cosmetic.

dogwood-diseasesAnthracnose                                      Dogwood Borer                                     Powdery Mildew

Choosing Healthy Trees

Buy from a reputable grower—Don’t bring disease home! Buying a healthy Tree from a reputable nursery is always smarter than taking a chance with a Tree from a cut-rate grower, but it’s especially important with Trees that are vulnerable to serious diseases, like Dogwoods.

At Bower & Branch™, our number one goal is your success. This means growing intelligently, patiently, and intentionally, so your Tree arrives at your home ready to grow without interruption. This means reducing Tree stress at the nursery, because stressed Trees are predisposed to disease and insect attacks. This means growing a strong, healthy root system, even if doing so means taking longer to get that Tree to market.

After growing Dogwoods in containers for many years, our growers have mastered the techniques required to produce healthy and vigorous Trees:

1) Water—Managing irrigation for container-grown Dogwoods is tricky. They’re kind of the “Goldilocks” of Trees—always wanting that “just right” amount of water. It’s a difficult job requiring hands-on management, but we’ve learned that the payoff is worth the trouble. Proper water management produces optimum root growth and a sturdy, healthy Tree. The Bower & Branch™ Water Element you use at home ensures that the right amount of water is supplied to your Tree after it leaves the nursery. This great tool allows you to be a water expert, too!

2) Fertilizer—The Bower & Branch™ Fertilizer and Soil Enhancer that you use at home is the same product we use at the nursery. It encourages a moderate growth rate that is best for the long-term health of your Tree. High-nitrogen fertilizers used at other nurseries produce a saleable Tree more quickly, but at the expense of lush, weak growth that is more vulnerable to disease.

3) Pesticides—On the nursery, we do apply preventive pesticides from time to time as required. We grow intensively, so pests are attracted to the large number of Trees we grow. This is not at all like the conditions you have at home, and we do not recommend a preventative pesticide program for your Dogwoods. Healthy Trees defend themselves without use of costly chemicals. Empower your Tree with proper watering and fertilization instead!

Our growers are happy to tell you more. Please feel free to contact them at grower@bowerandbranch.com.

Consider other varieties of Dogwood Trees—Our native Flowering Dogwood is a magnificent Tree, and some homeowners will settle for nothing else. However, there are many other beautiful Dogwood Trees to choose from that are much more resistant to insects and disease.

Asian Kousa Dogwoods are very resistant to the problems that affect Flowering Dogwoods. They bloom a bit later than Flowering Dogwoods and have equally showy flowers, edible fruit, and colorful fall foliage. Samaritan® Kousa Dogwood is an especially attractive form with variegated white and green foliage throughout the growing season.

The Rutgers Hybrid Dogwoods from Rutgers University are exciting new trees that have excellent disease resistance over the standard varieties. Stellar Pink® and Celestial® are two popular selections. We are particularly fond of the Starlight® Hybrid Dogwood, which has extra-large white flowers in late spring.

samaritan-and-starlight-dogwoodCornus Samaritan                                                                 Cornus Starlight

Care of Dogwood Trees

Proper care is the key to helping your Dogwood Tree avoid pests and disease. There are a few steps you can take to help your Dogwood Tree live a long, happy life. Proper care starts at planting. At planting, be sure to:

• Choose a site that’s sunny in the morning (so foliage can dry out after being damp all night) and that has good air circulation.
• Plant the rootball two inches higher than grade. This ensures good drainage.
• Fertilize your Dogwood with Bower & Branch™ Soil Enhancer and Fertilizer Element.
• Spread 3-4 inches of mulch around the Tree, but don’t heap it up against the trunk.

As you continue to care for your Tree throughout its life, make sure you:

• Water well during dry periods, but don’t over water your Dogwood. The Bower & Branch™ Water Element will ensure the proper amount is supplied.
• Don’t allow sprinklers to spray water on the Tree’s leaves. Many diseases thrive in moist, humid conditions.
• Never allow lawnmowers or string trimmers to damage the bark and provide an easy access point for insects or disease.
• Prune out any dead Dogwood branches promptly, so disease can’t spread further. Destroy all clippings—don’t compost them. The same goes for fallen leaves that may have a chance of harboring disease.

Additional Tips

Native Dogwoods have been an important part of our landscapes since Colonial times, and many beautiful old specimens attest to the fact that well-cared for Dogwood Trees can still expect to live a long life. The pests and diseases that affect them usually only attack Trees that are weakened to begin with.

The best thing you can do to help your Dogwood fight off these problems is to focus on soil health. This means proper watering and fertilization. Fertilizing with the Bower & Branch™ Soil Enhancer and Fertilizer Element will improve your soil and give your Tree the proper levels of the right nutrients as it needs them. When well-nourished, your Dogwood will activate its own natural defenses to ward off pests and diseases. Take care not to over-fertilize, as too much fertilizer can be bad for your Tree’s health, too. The Fertilizer Element alone will supply all your Tree needs.

If you do suspect your Dogwood Tree is showing symptoms of anthracnose, borers, or some other problem, please do not hesitate to contact us at grower@bowerandbranch.com. We’ll help you with a plan of action to get your Tree back to good health. Even if your Tree does contract one of these problems, it doesn’t have to be a death sentence if it’s caught early. Your Tree might just need a little help to get back on its feet.

You Can Still Grow Dogwood Trees

Although you might have heard some dire news about Dogwood Trees in the news recently, you don’t have to give up on growing these noble specimen Trees. Buy a healthy Tree, treat it well, and keep an eye out for problems, and you should get many, many wonderful years out of your Dogwood Tree!

 

Dogwood Anthracnose Image: Robert L. Anderson, USDA Forest Service, Bugwood.org

Dogwood Borer Image: James Solomon, USDA Forest Service, Bugwood.org

Powdery Mildew Image: John Hartman, University of Kentucky, Bugwood.org

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