Pests in the Garden: Battling Citrus Leafminer and Spider Mites

Citrus growers face a persistent threat from the Citrus leafminer. These pests cause significant damage by creating serpentine mines within the leaves, which can lead to leaf distortion, reduced photosynthesis, and overall weakening of the tree. The citrus leaf miner is particularly problematic in warmer climates like Perth, where it can thrive and reproduce rapidly.

A leaf miner is any one of numerous species of insects in which the larval stage lives in, and eats, the leaf tissue of plants. The vast majority of leaf-mining insects are moths, sawflies and some beetles.

Larvae mine their way through leaves creating blisters that often look like yellow, squiggly lines in the leaves.

The life cycle of a leaf miner has the following stages:

Egg
Larva
Pupa
Adult moth
Adults do not damage plants and live only 1 to 2 weeks. Adult moths are most active in the morning and the evening and spend the day resting on the undersides of leaves, but are rarely seen.

Eggs hatch in 3-6 days. Often there are several larvae within each mine.

The newly hatched legless larvae will burrow into the interior of the leaves to begin feeding. When the larvae are mature they will chew through the leaf surface, drop to the ground, and pupate.

While citrus leafminers can affect leaves of all ages, they particularly target young, tender foliage, causing specific types of damage:

Leaf Deformation: As citrus leafminer larvae tunnel through the young leaves, they disrupt the normal growth and development of leaf tissue. This can result in the deformation of affected leaves, causing them to curl, twist, or become puckered. Deformed leaves not only detract from the aesthetic appearance of the citrus tree but can also impair the tree’s ability to photosynthesize and produce energy.

Reduced Photosynthesis: The serpentine mines created by citrus leafminer larvae can interfere with the leaf’s ability to capture sunlight and conduct photosynthesis effectively. As a result, affected leaves may exhibit reduced chlorophyll production and decreased photosynthetic activity, leading to overall reductions in plant growth and vigour.

Stunted Growth: Severe infestations of citrus leaf miners can significantly stunt the growth of young citrus trees. When a large proportion of the young leaves are affected and damaged by leaf miner larvae, the tree may struggle to allocate resources for new growth, resulting in diminished overall size and vigour.

Control Measures:

Weed control helps reduce populations
Remove infected leaves and put them in a bin, not compost.
Avoid pruning live branches more than once a year, so that the cycles of flushing are uniform and short. Once the leaves harden, the pest will not be able to mine the leaves.

Leafminer Recipe: Homemade white oil

• 1 part oil (olive, sunflower, fractionated coconut, any oil will do)
• 1 part dishwasher liquid
• 1 part water

Add to a small jar- shake till white- then this is your concentrated solution. Put 1 tablespoon to a spray bottle with water and spray affected plants.

Overall, the damage caused by citrus leaf miners especially to young leaves can have significant implications for the health, growth, and productivity of citrus trees. Effective management strategies, such as regular monitoring, cultural practices to promote tree vigour, and targeted treatments with natural remedies like white oil spray, are essential for controlling citrus leaf miner populations.

Please share this article with your friends and family, knowledge is power and together we can unite and stand against leaf miner.