How to Identify and Prevent Catfacing of Tomatoes

You nurture your tomato plants until you have beautiful fruit maturing on the vine. Upon closer inspection, you discover that something has gone terribly wrong.

Your fruits have a hideous deformity! What is going on?

A close up of a deformed tomato growing on the vine, pictured on a soft focus background. To the top and bottom of the frame is green and white text.

Fear not – they are not under siege from a pathogen that could ruin your entire crop.

In fact, if the fruit have not split open, they are perfectly safe to eat. However, you certainly can’t sell them or show them off.

We will introduce you to the world of tomato disfigurement known as catfacing – a disorder that is not contagious, but can cause significant losses of yield.

Here’s what I will cover:

What Is Catfacing of Tomatoes?

How did this disorder get its name? The answer is simple: because the deformity looks similar, at least at times, to a small cat’s face.

A close up of a red fruit with a deformity that has caused scarring on the bottom side, pictured on a soft focus background.
Photo by Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org, via CC BY-SA.

A physiological disorder rather than a disease, catfacing is not caused by an insect or pathogen – it is caused by cultural problems in the garden.

The result is fruit that is deformed on the blossom end, or sometimes on the side.

A close up of an unripe, green fruit suffering from a condition that causes deformity, pictured on a soft focus background.
Photo by Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org, via CC BY-SA.

Typically, you will see a large indentation that looks like a scar. It can crack open and expose the locules – the cavities that contain the seeds.

The fruit can also become distorted and misshapen.

However, even if the blossom scar is just enlarged and the fruit has not split open, the tomato is still considered to have catface.

What Causes This Deformity?

The exact cause is unknown, but many cultural conditions have been associated with catfacing.

Abnormal Temperatures

Cool weather has been associated with the development of this disorder. Temperatures that dip below 60°F three weeks before the plant blooms may interfere with normal development of the flower bud, which can manifest in catfacing.

Abnormally hot weather can also induce this condition.

Even worse is when there are wide fluctuations between temperatures at night and during the day.

This can cause the fruit to alternate between slow growth and quick growth – a situation that is ripe for the development of catfacing.

Disturbance to the Flowers

Physical damage to the flowers, before or after pollination can cause catfacing.

A common source of injury to the flowers is an attack by little insects called thrips. Leaf curl is a major symptom of thrip infestation.

You definitely want to treat your plants if they have an infestation of thrips.

These insects can transmit tomato spotted wilt virus, which could destroy all of your tomato, pepper, and other nightshade crops.

A close up of the packaging of Bonide insecticidal soap to treat plants infested with pests.

Bonide Insecticidal Soap

You can banish thrips by spraying your plants with an organic soap-based spray, according to package instructions, such as Bonide Insecticidal Soap available from Arbico Organics.

Pruning and High Nitrogen Levels

According to experts at UMass Extension, excessive pruning or high concentrations of nitrogen in the soil may also cause catfacing.

Dr Gerald Brust from the University of Maryland Extension suggests that the reduction of auxins – plant hormones that promote cell elongation – as a result of pruning may increase susceptibility to this disorder.

Herbicide Exposure

In commercial operations, tomatoes that have been exposed to the herbicide 2,4-D can develop this disorder. The chemical mimics plant hormones, so it can disrupt the normal development of the fruit.

Fortunately for the home gardener, edible crop exposure to chemical herbicides is unlikely.

Tomatoes That are Affected

Very large tomatoes, flat-bottomed cultivars in particular, appear to be more prone to develop this condition than smaller varieties.

Heirloom varieties are frequently vulnerable, and you may have noticed the telltale signs of this physiological disorder on fruit at the farmers market. Fortunately, as long as damage is not severe, it does not render the fruit inedible.

How to Prevent Catfacing

While you may not be able to prevent the development of catface entirely, you can take steps to minimize its likelihood.

Grow Resistant or Tolerant Varieties

Growing tolerant varieties is highly recommended as the best way to avoid catfacing.

There are several varieties that are less likely to develop this disorder, including ‘Countil,’ ‘Duke,’ ‘Floradade,’ ‘Monte Carlo,’ and ‘Walter.’

‘Floradade’

You can find seeds for ‘Floradade’ in a variety of packet sizes at Eden Brothers.

Avoid Low Temperatures

If you grow your plants in a greenhouse for any part of their life cycle, avoid low or fluctuating temperatures.

And don’t plant your transplants in the ground too early, so they will be less likely to be exposed to cold weather.

If a cold snap is in the forecast, protect your plants with loosely wrapped burlap or a few layers of towels.

Do Not Prune or Fertilize Excessively

While it can be tempting to fertilize your young plants with nitrogen, do so in moderation. Conduct a soil test to check the nutrient levels of your soil and find out if there is a deficiency.

Also, avoid pruning aggressively, particularly during bloom time.

Maintain Adequate Levels of Moisture

Tomato plants require regular, deep watering.

Mulching well is one way to keep more moisture in the soil and reduce the chances that your fruit will develop catface.

Another is to water thoroughly with a soaker hose at the soil level.

Cracking Can Increase Vulnerability to Pathogens

Some split tomatoes are safe to eat, but splitting can cause a potential pathway for fungi and bacteria to enter the fruit.

A close up of a ripe red fruit suffering from a deformity to the fruit known as catface, pictured on a dark background.
Photo by Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org, via CC BY-SA.

Black mold rot is a particular problem. This can be caused by several different types of fungi, particularly Alternaria alternata.

Harvesting as soon as they are ripe can minimize the chances of contracting this infection.

Experts advise against eating any fruit with catfacing that has exposed tissue. More superficial damage to the skin can be removed before enjoying the fruit.

Fungi can produce very dangerous toxins, and you do not want to take any chances by eating fruit that could contain them.

Many Factors Cause Catface, But There Is Hope

A who’s who of environmental factors can cause catface. These include low or fluctuating temperatures, excessive pruning and fertilization with nitrogen, flower damage from thrips, and herbicide drift.

A close up of a ripe red fruit suffering from a condition known as catface that causes scarring and disfigurement.

While many of these are out of your control, you can take steps to minimize the chances of this disorder occurring.

Planting tolerant or resistant varieties is your main line of defense. If your crop suffered this year, try a resistant cultivar next season. Wait to plant your transplants until soil temperatures are above 55°F.

Once plants are in the ground, be sure to water regularly and thoroughly, and mulch around plants to retain moisture.

Have you had a problem with catface on your crops? Let us know in the comments below!

And to learn more about growing tomatoes in your garden, check out these guides next:

© Ask the Experts, LLC. ALL RIGHTS RESERVED. See our TOS for more details. Product photo via Arbico Organics. With additional writing and editing by Clare Groom and Allison Sidhu.

About Helga George, PhD

One of Helga George’s greatest childhood joys was reading about rare and greenhouse plants that would not grow in Delaware. Now that she lives near Santa Barbara, California, she is delighted that many of these grow right outside! Fascinated by the childhood discovery that plants make chemicals to defend themselves, Helga embarked on further academic study and obtained two degrees, studying plant diseases as a plant pathology major. She holds a BS in agriculture from Cornell University, and an MS from the University of Massachusetts Amherst. Helga then returned to Cornell to obtain a PhD, studying one of the model systems of plant defense. She transitioned to full-time writing in 2009.

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