Diseases and Issues For Tomatoes

Diseases and Issues that can impact your Tomato Plants and the Fruit.

The feature image is a picture of Cat Facing on a tomato.

Catfacing:  This looks like depressions or scaring on the bottom of the tomato by the blossom end, it can be caused by cold temperatures when flower buds are forming.  Avoid planting too early to prevent this.  The tomato will still ripen and taste fine it just does not look as nice as those not impacted by catfacing.

Cracking: Cracking (from stem to blossom end) is caused by high temperatures when rain follows a dry spell or from watering overhead followed by high temperatures (This is why you should not water tomato plants overhead).  The top two tomatoes have cracks, tomatoes still tasted great.

Cat Facing

Sunscald: Too much sunlight and a combination of heat cause yellowing blistering of the tomato skin, it can also be due to the loss of too many leaves either from pruning or disease-causing leaves dropping.  You can prevent this by shading your plants if the weather is going to be too hot by using frost cloth.

Leaf Roll:  Edges of leaves curl up to form a cup, sometimes the leaves are firm and leathery feeling.  To prevent this make sure that your soil is well-draining and loose.  If you have clay soil you need to amend the soil since clay soil holds water.  There are many possible reasons for leaf curl.  Too much water and nutrients are not being absorbed by plants, root damage, and results from heat stress.

Verticillium & Fusarium Wilt:  Causes leaves to curl up, turn yellow, and drop off and plant to wilt.  If this is severe there is no way to stop the disease, you need to dispose of the plant to prevent it from spreading to others, bag it up, and throw it in the garbage.

Blight:  Dark sunken areas form on leaves as the first fruits start to mature (Early).  Black, irregular water-soaked patches on leaves, dark spots on fruit (Late).  Destroy or dispose of affected plants.  The best defense is to plant disease-resistant cultivars.

Blossom End Rot: Fruit forms a water-soaked dark spot on the blossom end of the tomato that can eventually take over half the affected fruit.  This is mostly caused by calcium deficiency or uneven soil moisture.  Blossom end rot can also be caused by damaged feeder roots from careless transplanting.  When planting, use mulch to help with moisture; handle seedlings gently.

It is important to be consistent and provide deep watering, when watering apply the water to the roots only and not the leaves.  Tomatoes need about 1 inch of water per week.  When you water too often you can deplete the calcium being taken in by the plant.

If you have blossom end rot on your tomatoes remove the tomatoes and throw them away.  To keep other tomatoes from getting blossom end rot you need to adjust the watering schedule and provide calcium-rich fertilizers to the plant.

Yellowing Leaves:  This is due to one of several reasons, nutrients not being absorbed by the plant, overwatering, or leaves crowded and not getting enough sunlight.  Best to remove the yellow leaves, this should not be an issue for the fruit or plant going forward.,

Be sure that you are not watering the leaves it is best to water using drip or soaker hoses.

Internal Rot:  This can be caused by water accumulating at the top by the stem and water seeping inside the tomato causing it to rot from inside.  This water accumulation can be from overhead watering or rain and dew collecting by the stem or cracks on top of the tomato.


Flea Beetles:  They feed on tomato foliage early in the season.  Plant hardened larger, sturdier transplants in warm soil as prevention.  Cultivate your soil in the fall or early spring to disturb the overwintering adults.  Cover seedlings with floating row covers.

Tomato Hornworms: Can be controlled by hand-picking them off the plants, or applying the selective bacteria Bacillus thuringiensis (Bt).  To prevent them from invading your tomatoes you can plant basil throughout your tomato plants to deter hornworms.

Snails and Slugs:  These ubiquitous garden gastropods will feast on fruits too close to the ground.  Trellis your plants to avoid losses.  Use baited traps with bread dough, beer, or Sluggo to kill them.

Diseases and Issues for Tomatoes Recap

Even though there are many diseases and issues that tomatoes face it is well worth the effort to grow them and you can be very successful at growing tomatoes with a little work.

Also, you can minimize the diseases and issues for tomatoes by selecting the varieties that grow the best in your climate, check with your local garden shops or local extension offices for the best tomatoes to grow.

Tomatoes need to be watered consistently and deeply through soaker hoses or a drip system to keep the water off the leaves and provide it to the roots.  Too much water can lead to several issues, typically 1 inch per week is what is needed to grow healthy and disease-resistant tomatoes.

Now that you know what diseases and issues for tomatoes it is time to grow your own tomatoes.  The flavor of a homegrown tomato cannot be beaten.

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