Common Summer Tree Pests & How to Spot Them with Alt Arb Ltd Part 2

In June, we looked at common summer tree pests and how to spot the early signs of trouble. This month, we’re diving deeper—focusing on a tree species we often get called out to inspect: Poplars.

Fast-growing and elegant, Poplar trees are popular in residential and commercial landscapes for their height and structure. But they’re also highly susceptible to pests and diseases, especially during warm, wet summer months.

Here’s what to watch for if you have Poplars on your property.

1. Yellow Mildew (Rust & Leaf Spot Fungi)

What to Look For:

After heavy summer rain, Poplars are prone to developing yellow mildew, often appearing as discoloured patches or a dusty yellow coating on the upper surface of the leaves. This may be accompanied by black or brown spotting underneath.

This condition is caused by fungal pathogens that thrive in moist conditions. While not immediately deadly, it can weaken the tree and lead to premature leaf drop, affecting growth and appearance.

Signs of Damage:

• Yellow powdery coating on leaves

• Brown or black speckles on undersides

• Early leaf fall

• Thinning canopy

👉 Tip: Improve air circulation around your tree by removing crowded growth or ivy, and clear fallen leaves to reduce reinfection.

2. Oak Processionary Moth (OAP Moth)

What to Look For:

Although originally a threat to oaks, oak processionary moth (OAP moth) caterpillars are now occasionally found on Poplars—especially in more urban areas where multiple species are planted together.

These caterpillars are dangerous—not just to trees but to humans and pets too. They release toxic hairs that can cause skin irritation, eye problems, and even breathing issues.

Signs of Damage:

• Webbed nests on the trunk or large branches

• Stripped leaves

• Clusters of tiny hairs or irritating fibres on or around the tree

• Irritated skin after contact

⚠️ DO NOT attempt to remove these nests yourself—this is a job for trained professionals with protective equipment.

3. Tree Borers (Including Poplar Borer Beetles)

What to Look For:

Tree borers, such as the Poplar Borer Beetle, tunnel into the trunk and branches, disrupting the flow of nutrients and water through the tree. Once inside, they’re difficult to detect until significant damage has been done.

Adult borers often target stressed trees, which makes already-weakened Poplars particularly vulnerable.

Signs of Damage:

• Tiny round or oval holes in bark

• Sawdust-like frass (borer waste) around the base

• Wilting or yellowing leaves

• Branch dieback

• Peeling or damaged bark

⚠️ Early detection is critical. If you notice borer holes or frass, book a professional inspection immediately.

How Alt Arb Can Help

At Alt Arb, we offer expert diagnosis, treatment plans, and preventative care for Poplars across Gloucestershire. Whether it’s managing mildew, removing dangerous moth nests, or assessing internal borer damage, we have the skills and equipment to keep your trees safe, strong, and thriving.

We also offer:

• Tree health surveys

• Targeted pest and disease treatment

• Tree pruning to reduce vulnerability

• Safe tree removals when necessary

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Concerned About Your Poplars?

If you spot any of these signs—or just want peace of mind—get in touch. Our experienced tree surgeons will inspect your trees, explain your options, and provide professional care to protect your green space.

Contact Alt Arb today for expert Poplar inspections and pest management services in Newent, Gloucester, and surrounding areas.

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