Skip to Content

White Spots on Lemon Tree Leaves (How to Handle It)

I was watering a lemon tree in June when I noticed some odd white spots on the leaves.

At first, I wrote it off as a physiological effect and paid it little mind. However, as the days progressed, I became concerned about the growing number of white spots.

I looked for rust, powdery mildew, and scale insects, but I couldn’t figure out what was wrong.

In this article, I’d like to talk about the white spots on the lemon leaves and how things are going now that I’ve taken them off.

What Are Those White Spots on Lemon Leaves?

You can see the lemon’s white spots in the photo below. Around the first of June, they began to appear on some of the leaves, and as the month progressed, they spread to the remaining leaves.

The small white spots on the leaves grew more prominent over time.

So far, I’ve come up empty in my search for a disease that affects lemons. It didn’t look like powdery mildew, black spot, or anthracnose.

The scary thing is that the white spots that were small at first have grown, and the number of leaves with white spots has gone up.

I decided to cut these leaves off because I thought it was a bad idea to leave them alone.

After I pruned and cut off the branches before, new shoots have been growing, and the top of the tree has become bushy with beautiful yellow-green leaves.

It was a sloppy pruning job, but it seems to have worked out.

After two weeks, the yellowish-green shoots have fully developed into mature green leaves. The upper leaves are pretty firm.

Leaf Miners

Insects, known as leaf miners, are the likely culprits of mining-like white spots, as seen in the following picture. They’re not all that cute, though.

The tiny caterpillars, which range in size from 2 to 3 mm in diameter, can be seen if one carefully examines the tips of the leaf spots.

For example, you can see a small caterpillar about 2 to 3 mm long hiding in the leaf.

Leaf miner caterpillar hiding under the leaf

Do I take the whole leaf off?

Crush the larvae?

…I squished it. I’m sorry.

Powdery Mildew

Powdery mildew, also called a white lemon mold or simply white mold, is one of the most widespread fungal diseases.

The condition is triggered by high temperatures, high humidity, and a lack of air movement.

It’s easy to spot because the leaf-smothering fungus leaves a white powder on the leaves, which stops chlorophyll from doing its essential job of photosynthesis.

After the leaves turn yellow, they will become powdery and fall off.

Spraying with a solution of water and 0.5% bicarbonate is an effective biological treatment for white powdery mildew.

Pruning Regenerated Lemon Tree

Pruning Lemon Tree Leaves with White Spots

After researching, I determined that it was a sign of a disease, probably powdery mildew or rust. However, a closer look revealed that it could be the work of a scale insect.

I couldn’t think of anything else to do, so I just hacked it off with some scissors.

I was so confused by all the information that I even cut off a branch.

I cut off the side branch that was the only one of the three that was growing sideways.

I lopped off about seven or eight spotted leaves to see what would happen. Unfortunately, the leaves on the branch I cut are also problematic.

After Cutting Leaves With White Spots

It’s nice that the leaves with lots of white spots are gone. I will see how this goes for a while.

After Observing For A Month

What happened to the lemon plant one month after the leaves were cut off?

My lemon tree is growing normally.

And the white spots, which were thought to be a problem and might be a disease, have not been confirmed as of yet.

Now, I am glad that cutting off the leaves was the right thing to do.

However, because we do not know what causes the disease, the same symptoms may appear in the future.

With some assistance, I could fix the problem this time, but if we keep doing the same thing, the plant may lose all of its leaves and die.

In the future, I’d like to do some additional research on this.