Curling leaves with bumps
Citrus tree leaves can curl when temperatures are either very cold or extremely hot as this is a sign of distress on the tree. Another sign of distress on trees is when the leaves form little bumps on them. Distress can be caused by giving too much or too little water to the plants, but it is mostly due to an insect infestation. A quite common insect infestation in citrus trees is curl leaf aphids.
The aphids feed on the plants, sucking out all the nutrients which cause the leaf to curl around it. The curling of the leaves in turn, effects the plant’s ability to collect sunlight for energy production resulting in a loss of necessary nutrients. Large numbers of these aphids on a plant can cause the leaves to go yellow which then falls off causing distorted growth in the plant.
Aphids are small, soft-bodied insects shaped liked a pear. They cluster densely together on new shoots/growths or underneath the plant leaves. They can be found in many different colours ranging from green, black, red, or even yellow. Aphids release a sweet fluid on the leaves, called honeydew. This in turn attracts ants. The best remedy for the leaves that have curled with bumps on is to remove them immediately and destroy them, in order to stop the spread even further.
Prevention and control
- Firstly, remove all the infected leaves and branches, and destroy it.
- Remove as many aphids on the plant as you can with a strong stream of water.
- Use a soapy mixture or neem oil and repeat the process if needed.
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The curled leaves tend to also give protection to the aphids as insecticides just runs off, leaving the aphids unharmed. Thus, removing by hand and continuous treatment with neem oil will help to control it better. Other natural ways would be to release beneficial insects into your garden such as ladybugs and lacewings.