Magnolia Scale: Identification, Treatment, and Prevention Tips

Introduction

Magnolia trees are a beloved addition to any landscape, offering stunning blooms and a robust presence in gardens. However, like all trees, they can face challenges, one of the most common being magnolia scale. This pest can cause significant damage if left untreated and, in Northwest Indiana, is starting to feed on our Magnolia trees as we move into Summer. In this blog post, we'll explore what magnolia scale is, how to identify it, and effective ways to manage and prevent it.

What is Magnolia Scale?

Magnolia scale (Neolecanium cornuparvum) is one of the largest scale insects found in North America. These pests primarily affect magnolia trees, feeding on the sap and weakening the tree over time. They appear as small, smooth bumps on branches and are often mistaken for natural tree growths or fungal infections.

Identifying Magnolia Scale

Magnolia Scale Adults in Summer. Source: Morton Arboretum

Appearance:

• Adult Females: Up to ½ inch in diameter, with a smooth, tan to brown appearance.

• Eggs: Laid under the female's protective cover, hatch into crawlers (young scales).

• Crawlers: Tiny, yellow-orange insects that move to new feeding sites on the tree.

Signs of Infestation:

• Honeydew: A sticky substance excreted by the scales, often leading to sooty mold growth.

• Branch Dieback: Severely infested branches may die off.

• Reduced Vigor: Overall decline in tree health, fewer and smaller blooms.

Lifecycle of Magnolia Scale

Understanding the lifecycle of magnolia scale is crucial for effective management. These pests have one generation per year:

Magnolia Scale crawlers in late summer. Source: Morton Arboretum

1. Eggs hatch: Late summer.

2. Crawlers: Move to branches to feed, eventually settling in one spot to mature and overwinter.

3. Adults: Mature scales appear by late spring to early summer.
   

Managing Magnolia Scale

1. Monitoring: Regularly inspect your magnolia trees, especially in late summer when crawlers are active.

2. Cultural Controls:

• Pruning: Remove and destroy heavily infested branches to reduce the scale population.

• Healthy Practices: Maintain tree health through proper watering, mulching, and fertilization.

3. Chemical Controls:

• Horticultural Oil: Effective against crawlers when applied in late summer. Ensure thorough coverage.

• Systemic Insecticides: Applied in early spring, these can provide season-long control by being absorbed into the tree’s system.

4. Biological Controls:

• Natural Predators: Encourage beneficial insects like lady beetles and parasitic wasps that prey on scales.

Preventing Magnolia Scale

Adult Scale and black Sooty mold on leaves and branches. Source: Minnesota State University

• Regular Inspections: Early detection can prevent severe infestations.

• Tree Health: Healthy trees are more resistant to pests. Regular care and maintenance go a long way.

• Integrated Pest Management (IPM): Combine cultural, biological, and chemical methods for sustainable control.

Conclusion

Magnolia scale can pose a significant threat to the health and beauty of your magnolia trees, but with vigilant monitoring and a comprehensive management approach, it can be effectively controlled. If you suspect your magnolia trees are infested, contact NWI ArborCare today. Let us help you keep your magnolia trees healthy and thriving!