Troubleshooting Tomato Problems

One of the most versatile and rewarding plants in a summer edible garden is the tomato. According to a 2014 study by the National Gardening Association, 86 percent of

Catfacing on tomatoes

homes with vegetable gardens grow tomatoes. It is understandable that the tomato plant is a popular home vegetable garden staple. Tomatoes offer thousands of different varieties options and flavors, plus, nothing beats the flavor of a ripe tomato straight from the garden.

When properly cared for, a single tomato plant can produce 10 to 15 pounds or more of fruit. If tomato yields aren’t what was expected or the fruit is damaged it could be due to a number of diseases, pests or abiotic disorders. Abiotic disorders result from nonliving causes and are often attributable to environmental or cultural factors, or simply to the plant’s genetic makeup. Below are five common abiotic disorders of tomatoes and recommended remedies from the UC Agriculture and Natural Resources publication, Growing Tomatoes in the Home Garden (publication number 8159).

Flower Drop and Failure to Set Fruit

The Problem: The blossoms fall off or the plant fails to set fruit.

Probable Causes:  Night temperatures are too low, below 55ºF, or daytime temperatures too high, above 90ºF. There could have been excessive smog during the blossoming period. Perhaps too much nitrogen fertilizer was applied or they are in too much shade. The plants might have been set out too early in spring or are not a variety that do well in our area.

Control: Choose varieties adapted to your climate zone, plant tomatoes in full sun, keep soil evenly moist, and avoid excessive nitrogen fertilizer. Hormone sprays can improve fruit set during low temperatures, but will not help in high temperatures.

Tapping on blossom stems 3 times a week at midday when flowers are open may improve pollination and help set fruit.

Sunburn

Problem: The fruit turns light brown and leathery on side exposed to the sun.

Probable Cause: Overexposure to sunlight.

Control: Maintain plant vigor to produce adequate leaf cover and avoid overpruning.

If needed, provide partial shade (e.g., shade cloth, screening material) during hours of most intense sunlight.

Leaf Roll

Problem: Older leaves roll upward and inward rather suddenly, become stiff to the touch, brittle, and leathery.

Probable Cause: High light intensity and high soil moisture, particularly when plants are staked and heavily pruned. Some varieties are more susceptible than others.

Control: Choose less-susceptible varieties. Try to maintain even soil moisture and provide partial shade during periods of intense sunlight.

Blossom End Rot

Problem: Water-soaked spot on blossom end of fruit enlarges and darkens, becomes sunken and leathery. Affects both green and ripe fruit, and is more common on sandier soils.

Probable Cause:Calcium nutrition and water balance in the plant, aggravated by high soil salt content and fluctuating soil moisture.

Blossom end rot in tomatoes is a common abiotic disorder

Control: Maintain even soil moisture. Amend planting area with organic matter such as compost to improve water retention. Avoid heavy applications of high-nitrogen fertilizer. Soils that are deficient in calcium may be amended with gypsum.

Fruit Cracks and Catfacing

Problem: Circular cracks around the stem end and cracks radiating outward from the stem. There may also be malformation and cracking at the blossom end (catfacing).

Probable Causes: Periods of very fast growth with high temperatures and high soil moisture levels. Wide fluctuations in soil moisture content or heavy rain following a dry period or wide differences in day and night temperatures. Catfacing may also be caused by abnormally cool or hot conditions. Disturbances to the flower parts during blossoming can also lead to fruit cracking. There are just some varieties that are more susceptible to cracks and catfacing than others.

Control: Choose varieties that are adapted to your climate zone and are less susceptible to cracking. Keep soil evenly moist and maintain good leaf cover or provide partial shade in periods of high light intensity. Adding a layer of organic mulch 3 to 4 inches deep such as compost helps moderate soil temperatures and soil moisture fluctuations.

 

Pests eating away at your tomatoes?
Other damages that are caused to tomato plants can be caused by a variety of pests. Some examples of common pests, include: hornworms, tomato fruitworms, tomato pinworms, stink bugs, white flies, and leafminers. For information about identifying and managing pests in your edible garden visit the UC Integrated Pest Management (UC IPM) website, ipm.ucanr.edu.

If you have a gardening related question you can contact the UC Master Gardeners at 209-953-6112. More information can be found on our website:  http://sjmastergardeners.ucanr.edu

 

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  • Blog Author

    Marcy Sousa

    Marcy Sousa is the San Joaquin County UC Master Gardener Program Coordinator. She is a Stockton native and enjoys teaching others about gardening. She has her bachelors from Stanislaus State in Permaculture. She has been with the program since 2007. Read Full
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