How to Get Rid of Fungus on American Elderberry Shrub

The American elderberry shrub is a popular ornamental plant prized for its showy flowers, fruit production, and medicinal benefits. However, like all plants, elderberries are susceptible to fungal diseases that can diminish their health and appearance. In this comprehensive guide, we’ll explore techniques for effectively treating and preventing fungal problems on your American elderberry shrub.

Common Fungal Diseases of Elderberry

Several fungal pathogens can infect elderberry shrubs, causing spots rusts, mildews and blights. Some of the most common include

• Powdery mildew – Caused by Erysiphe spp., appears as white powdery coating on leaves and stems

• Leaf spot – Sphaceloma and Diplocarpon fungi lead to small, dark spots on foliage

• Rust – Puccinia bolleyana causes yellow/orange powdery galls on stems and leaves.

• Cankers – Fungi like Cryptosporella cause sunken dead areas on bark.

• Fire blight – Bacteria Erwinia amylovora infects flowers and shoots.

While rarely fatal, these diseases can diminish fruit production, vigor, and aesthetic appeal if left unchecked. Monitor shrubs frequently to identify issues early before they spread.

Cultural Practices to Prevent Fungal Diseases

Implementing smart cultural practices is the first line of defense against fungal diseases on elderberry shrubs:

• Choose disease-resistant elderberry cultivars when available.

• Prune shrubs regularly to improve airflow and light penetration.

• Space plants adequately to allow air circulation.

• Avoid overhead watering and don’t overcrowd plants.

• Clean up and remove fallen leaves and debris around plants.

• Use mulch and improve drainage to prevent waterlogged soil.

Safely Using Fungicides on Elderberry Shrubs

If diseases persist despite preventive measures, fungicide application may be warranted. Always follow label directions carefully:

• Organic options include neem oil, sulfur, and copper sprays. Test first for phytotoxicity.

• Conventional fungicides like myclobutanil, propiconazole, and tebuconazole are effective.

• Only treat affected areas and alternate chemicals to avoid resistance.

• Avoid spraying blooms to protect pollinators and only use elderberry fruit/flowers as food/medicine after an appropriate waiting period.

How to Treat Specific Fungal Diseases on Elderberry

For each disease, integrate cultural practices with targeted organic or chemical treatments:

Powdery Mildew

• Improve air flow and reduce water on leaves.

• Apply neem oil or potassium bicarbonate weekly as needed.

• Use trifloxystrobin or myclobutanil fungicides if severe.

Leaf Spot

• Promote good drainage and prune affected foliage.

• Spray copper-based fungicides after leaf emergence.

• Rotate trifloxystrobin, tebuconazole, or chlorothalonil for stubborn spot.

Rust

• Prune out infected galls. Disinfect tools between cuts.

• Eliminate nearby sedges that host the rust fungus.

• Apply mancozeb or trifloxystrobin at first sign of disease.

Fire Blight

• Prune out infected shoots well below diseased areas. Sterilize tools.

• Use preventive copper sprays at leaf emergence and flower bloom.

• Avoid excess nitrogen fertilization and overwatering.

Left unchecked, fungal diseases can quickly deflate the ornamental and edible value of American elderberry shrubs. But with close monitoring, cultural prevention, and strategic fungicide use only when necessary, you can maintain healthy, productive plants for years to come. Proper identification and prompt treatment are key to staying one step ahead of any fungal issues.