How to treat scale on a lime tree | 5 Easy steps

Treat scale on lime trees by first identifying the bugs by looking for clusters of 1-2mm beetle shaped insects that cluster together. They are often dark brown but can range from orange to black. Trim off any excess lime branches with scale and spray the remaining areas with horticultural oil.

Rubbing alcohol can be used on scale infections of less than 10 bugs.

This article will explore how to treat scale on a lime tree in 5 easy steps. Check them out below.

Scale on my lime tree stem.

Steps to treat scale on a lime tree – 5 Steps

1. Identify your scale bugs

Look for round bugs that can be brown, black or orange. They will 1-3mm in length and sit in cluster on the leaves and stems.

2. Trim off any excess branches with scale

Look over your lime tree and trim off branches with lots of scale. Do this if your tree is dense and bushy and won’t be affected with a few less leaves.

3. Use rubbing alcohol on small scale infections

Use rubbing alcohol and apply it to scale insects with a cotton bud. This is best for infections of 10 or less scale.

4. Spray horticultural or neem oil on scale infections

Spray oil as directed on the label reaching all areas of the lime tree with scale including under the leaves, on stems and branches.

5. Check your lime tree in 1-2 weeks

If there are still scale present, repeat the process until they are all gone.

I have always had success with just trimming the excess leaves and branches and adding a horticultural or eco oil. These oils are mild and will not damage your lime tree. After a few weeks my lime tree was good as new.

How to identify scale bugs on lime trees

Identify scale bugs by looking out for little clusters of 1-3mm bugs that can range from orange to dark brown or black. Scale bugs generally will cluster together and sit on the leaves or branches of your plant. They will form a dark brown coating to protect themselves which look like little armored plate

Scale TreatmentUses
Trimming branchesIf you have a small, bushy lime with excess branches remove scale by trimming off the infected area. Do not put branches in compost.
Rubbing Alcohol  Small scale infections on lime trees. Great for small indoor trees.
Horticultural Oil (Neem Oil)  For larger infections, good in spring before insects have formed their hard outer coating.

Prune of any small lime branches with scale

If you have a small, bushy lime with excess branches remove scale by trimming off the infected area. Do not put branches in compost.

Apply rubbing alcohol to small scale clusters on lime trees

Rubbing alcohol is an easy way to treat scale insects on lime trees. This method works well if there are only a few scale insects. You will need to apply the rubbing alcohol with a cotton bud on each scale insect a few times. This is a great method for a small indoor lime tree but will be too difficult to use on a larger lime tree.

Using Horticultural oil on lime scale

To treat large scale infections on lime trees use horticultural oil or otherwise know as Neem oil or Eco Oil. These oils as they are a mild treatment that won’t harm your plant and is targeted to reach these types of pests.

Horticultural oil is usually necessary for larger infections and is good to apply in spring before insects have formed their hard outer coating.

Why scale insects are bad for lime trees

Scale insects will suck the sap out of the leaves and branches of your lime tree and excrete a sticky substance called honeydew. This substance sits on the leaves and stems and can attract mold which can stop your leaves from receiving sunlight and stop them from making food for the tree via photosynthesis.

Eventually scale insects will cause the tree to drop their leaves, can cause the leaves and branches to die off and can eventually kill the plant. They are particularly bad for young lime trees or those that have been transplanted as they are less established so less able to grow and replace the leaves lost.

Ants can also be attracted to the sugary substance excreted by the scale and will actually spread the scale infection further.

How to prevent scale on lime trees

The best way to prevent scale on lime trees is to grow a strong healthy tree that can overcome any small scale infections. Scale can detect when a tree is in distress by chemical signals sent out from the plant. Struggling lime trees are more likely to get scale infections compared to healthy trees so set your lime up for success to avoid scale.

Plant lime trees in soil rich in organic matter

Get your lime trees off to the best start by planting them into soil that has been improved with compost, worm castings and aged cow manure. This will give the lime tree the chance to spread out roots, developing a strong healthy root system so it can absorb the nutrients and water it needs.

Give lime trees nitrogen in their first year

When you first plant out your lime tree the goal is to set up a strong root system and leaves and branches so your lime can photosynthesize and make carbohydrates. Encouraging good leaf growth by feeding your tree with nitrogen rich liquid fertilizer like fish emulsion and a slow release nitrogen fertilizer like pelleted chicken manure will get your tree set for years of quality fruit.

Focus on grow the tree strong and healthy in the first year and then you can switch to fruit production by applying a fruit promoting fertilizer in spring. Sulfate of potash or an organic fruit promoting fertilizer will increase the potassium levels and encourage your lime to grow fruit.

Waiting for your lime to settle in before encouraging fruit growth will give it a strong healthy start and help it to resist scale infections.

Using soapy water to kill scale on lime trees

Soapy water on its own will not kill scale on lime trees especially if they have formed their hard outer shell. Soapy water can be used to thoroughly wash a lime tree to remove some of the excess honeydew and mold before adding horticultural oil.

I have always applied eco oil without using soapy water as I didn’t want it to get into my soil. Trimming off branches that are carrying large amounts of scale and spraying with oil should be enough to control the problem.

You may need to go back and apply more oil if the scale are still there, so keep an eye on them and make sure they are all gone before giving up on treating the scale.

How to treat scale on a lime tree: Summary

Scale are an annoying pest that can attack lime trees even if you have done everything right by the tree. Treating them is easy and most citrus gardeners will come across this at some point. Follow these 5 easy steps to get your lime tree healthy and scale free.

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