Tomato Talk

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In the 7 months of being a horticulture extension agent, I have begun to realize tomatoes are going to be a big part of this job. Almost everybody grows tomatoes in their home gardens. This week, I would like to discuss what issues you could be observing with your tomatoes around this time in July.

Adventitious Roots on Stem

You may have started noticing small, white growths or bumps on your tomato stems. Most likely you are seeing adventitious roots, or the earliest stage of developing roots.

Adventitious roots look like small, white bumps on stem.

Adventitious roots look like small, white bumps on stem. Photo credit: Missouri botanical garden

Tomatoes tend to do this when they are stressed. These bumps do not harm the plant. Some gardeners mistake these bumps for insects or disease.

Blossom End Rot

Blossom end rot is a common physiological disorder of tomatoes. Blossom end rot is characterized by a leathery lesion on the bottom of developing tomato fruit that progresses into general tissue collapse. This dead tissue then rots from secondary infection from molds and other fungi.

Blossom End Rot

Blossom end rot is characterized by a leathery lesion on the bottom of developing tomato fruit that progresses into general tissue collapse.

Improper pH, irregular watering and tilling too close to the root system can cause this problem. A quick fix would be to apply a calcium spray to the foliage of the plant.

Soil testing can help correct pH imbalances and keeping plants well-watered is also helpful.

Early Blight

Early blight is one of the most common tomato diseases. Symptoms include, lesions on lower leaves, look like brownish-black spots. In later stages, lesions may appear in the upper leaves and defoliation may occur in the lower part of the plant leaving the fruit susceptible to sunscald.

Early blight

Early blight symptoms include: lesions on lower leaves, look like brownish-black spots.

Lesions can expand to cover the entire fruit and are typically sunken, leathery, and dark brown to black with concentric rings.

Why you may be experiencing this is because this disease favors warm temperature and moderate to heavy rainfall.

Splitting and Cracking

This condition refers to the actual tomato. You could be experiencing this because of heavy rain, especially when preceded by dry weather, is the leading cause of fruit cracking and splitting in tomatoes. This type of damage is most likely to occur as tomatoes begin to ripen.

cracking tomato

Radial cracking seen commonly with rapid changes in soil moisture.

Cracking and splitting happen when rapid changes in soil moisture levels cause fruits to expand quicker than the tomato skin can grow.

There are two different patterns this damage may take.

Vertical splits along the sides of fruits are known as radial cracking and are the most serious. This pattern occurs with hot, humid weather.

Cracking that occurs in a circular pattern at the top of tomato fruits, ringing the stem end, is known as concentric cracking. You will want to harvest those immediately before they rot.

Leaf Curling

There are several issues that can cause tomato leaves to curl, including wet weather. That type of leaf curling is not cause for concern. There are also some varieties that are just more prone to leaf curling than others.

When excessive moisture is the cause of leaf curling, leaves curl upward starting from the bottom of the plant first. Leaves that curl as a result of wet soil conditions may take on a leathery appearance, but otherwise are still green and healthy.

Leaf curling could also be due to Herbicide damage. Tomatoes are very sensitive to drift from herbicides that have been sprayed in other areas. High humidity and wind can cause these products to drift, which will damage tomato leaves that come in contact.

Deformed leaves and buds along with stunting and lack of growth are signs of herbicide damage.

Conclusion

There are many more issues tomatoes can have, the previous listed are just the most commonly asked thus far in the growing season. You may be thinking “what can I do to prevent these things from happening to my tomatoes?” Here are some all-around good practices for growing tomatoes:

  1. Soil test- to know what nutrients your soil needs to produce a healthy crop
  2. Proper plant spacing- needed for multiple things like: overcrowding, air circulation, etc.)
  3. Rotating where you plant tomatoes.
  4. Monitoring- observe your plants. The sooner you detect a problem, the better.
  5. Regular watering
  6. Buy disease resistant cultivars. Take notice of the type of tomato plant you buy. If the name has V, F, FF, N, A in it, these are indicators that the plant is resistant to certain diseases. V = verticillium wilt F and FF = fusarium wilt N = nematodes T = tobacco mosaic virus A = Alternaria leaf spot.