Eliminating Mold on Arrowwood Viburnum Shrubs

As a popular ornamental shrub known for its showy white flowers and abundant fall berries, arrowwood viburnum (Viburnum dentatum) adds four-season interest to gardens and landscapes. However, like all plants, these shrubs can sometimes develop issues with fungal diseases like powdery mildew and botrytis mold. If your arrowwood viburnum is affected by mold, taking prompt action to treat and remove the mold will help restore the plant’s health and aesthetic appeal. In this article, we’ll cover techniques for effectively eliminating mold on arrowwood viburnum shrubs.

Understanding Arrowwood Viburnum Mold Issues

Arrowwood viburnums are susceptible to two common types of mold:

• Powdery mildew – This fungal disease manifests as a white powdery coating on leaf surfaces. It thrives in humidity and shade.

• Botrytis mold – Also called gray mold or blight, this fungus forms fuzzy grayish patches on leaves, stems, flowers, and fruit Wet conditions promote its growth.

While mold on arrowwood viburnum is usually not lethal, a severe infestation can weaken the plant, reduce flowering and fruit production, and create entry points for other diseases. Keeping mold under control is important for the health and appearance of your shrub.

Cultivating Conditions that Discourage Mold Growth

The first line of defense against arrowwood viburnum mold is promoting growing conditions that discourage fungal pathogen growth:

• Choose disease-resistant arrowwood cultivars like ‘Blue Muffin’ and ‘Chicago Lustre’.

• Provide good air circulation with proper spacing between plants.

• Avoid excessive shade and prune overcrowded interior branches to increase sunlight.

• Water at the base of the plant and avoid wetting foliage.

• Apply an organic mulch layer to reduce soil splashing onto leaves.

• Clean up and remove fallen diseased leaves and debris around the shrub.

Taking these preventive measures creates an environment less conducive to mold growth. But if mold still occurs, promptly treat affected plants.

Removing Infected Plant Parts

At the first sign of powdery mildew or botrytis mold on your arrowwood viburnum, pruning out the infected portions can help stop it from spreading. Here’s how to do it safely:

• Sterilize pruning shears in a diluted bleach solution between each cut.

• Remove any leaves or stems covered in white powdery mildew growth.

• Cut out grayish sections of botrytis-infected leaves or stems back to healthy tissue.

• Take out whole branches if mold is extensive. Retain the overall shape.

• Bag up and dispose of infected trimmings. Don’t compost them.

• Avoid pruning in wet conditions when mold spreads easily.

Though labor intensive, diligent removal of infected plant tissue can eliminate arrowwood viburnum mold before it gets out of hand.

Applying Fungicidal Sprays

For moderate to severe mold infestations, combining pruning with fungicidal sprays is most effective. Some options include:

• Neem oil – Derived from the neem tree, this organic oil coats leaf surfaces to smother fungal spores.

• Baking soda – Mixed with water and a small amount of mild liquid soap, baking soda raises pH levels to inhibit fungal growth.

• Sulfur – Available as a dust or spray, sulfur has antifungal properties that fight powdery mildew.

• Copper fungicides – Copper soap or copper sulfate sprays deter mold growth. Avoid contact with plant stems.

• Chlorothalonil – This common fungicide is available under brand names like Daconil and Ortho Max Garden Disease Control.

Always follow label directions carefully for any fungicidal product. Thorough coverage of leaf undersides is key for effectiveness. Repeat applications weekly or after rain. Combining fungicides with different modes of action helps prevent fungal resistance.

Maintaining Vigilant Monitoring and Care

Be vigilant about checking your arrowwood viburnum regularly for signs of fungal growth. Catching mold early makes treatment much easier. Ongoing care like proper watering, fertilization, and pruning also keeps your shrub strong enough to resist diseases. Remove any branches damaged by mold to improve air circulation.

If mold problems persist, consider testing your soil to check pH and nutrient levels. Excessive shade or acidic, compacted soils create conditions mold pathogens thrive in. Amending these issues can make your arrowwood viburnum less susceptible long-term.

With a dedication to prevention, early treatment, and consistent monitoring and care, you can keep arrowwood viburnum mold at bay and enjoy the beauty of a healthy, mold-free shrub for years to come. Don’t let fungal diseases detract from the ornamental appeal of this classic landscape plant – take action at the first sign of mildew or mold!