Mulberry leaf roller

The Mulberry leaf roller (Olethreutes mori) is a moth species belonging to the Tortricidae family. It is a common pest that specifically targets mulberry trees and can cause significant agricultural loss.

The adult moth is small and has cryptic coloration on its wings, which helps it blend perfectly with the bark of trees, making it difficult for growers to spot during the day.

The life cycle consists of the egg, larval, pupal, and adult stages. The larvae are highly active and often drop from the leaves on silk threads when they feel disturbed by external factors.

The development time of the larvae is heavily influenced by ambient temperature, with warmer spring weather leading to a faster transition from overwintering to active feeding.

Overwintering usually takes place in the pupal stage, hidden within the crevices of tree bark, deep in organic matter under the tree canopy, or in dry leaves.

Mulberry trees are the primary host for this species. The larvae feed on the leaf tissue, often rolling the leaves and securing them with silk threads to feed from within.

Feeding damage reduces the photosynthetic capacity of the tree, which can lead to stunted growth, particularly in young mulberry plants that are still establishing their structure.

Severe infestations can lead to complete defoliation of certain branches, stressing the tree and making it susceptible to secondary fungal or bacterial infections.

In addition to foliage, the larvae may consume tender terminal buds, which distorts the growth pattern and results in a bushy, unhealthy appearance of the tree.

The reduction in leaf area directly correlates with lower yields and decreased vigor, negatively impacting the tree's overall health and long-term productivity.

The most diagnostic sign of infestation is the presence of rolled or folded leaves, which the larvae use as protective nests during their feeding phase.

On the surface of the affected leaves, you will notice jagged feeding marks and areas where only the leaf skeleton (veins) remains, leading to browning and necrosis.

Silk threads are visible across the leaves and stems, indicating the activity of the larvae and their tendency to connect multiple leaves to form a secure habitat.

The presence of larval excrement (frass) on lower leaves or around the base of the branches is a clear indicator of a high population of active larvae in the canopy.

Deformed terminal shoots and stunted growth of new branches are reliable signs that the larvae have been feeding on the most succulent parts of the tree.

Mechanical control involves the systematic collection and destruction of fallen leaves and organic debris under the trees to reduce the overwintering population.

Sanitary pruning is essential; removing infested branches during the growing season helps to immediately decrease the number of larvae and slow down the spread of the pest.

Biological control using microbial insecticides based on Bacillus thuringiensis is effective, especially when applied at the early larval stages of the pest.

Chemical control should be used as a last resort, focusing on targeted spraying with selective insecticides that minimize harm to beneficial insects in the orchard.

• Monitor populations using pheromone traps.
• Scrape bark to remove overwintering sites.
• Promote biodiversity to encourage natural predators.
• Use systemic insecticides during peak activity.