Are your tomatoes not looking their beautiful best this year? They may be suffering from blossom end rot.
End rot is not caused by a disease or a pest. It is a physiological problem caused by a low level of calcium in the tomato fruit. This calcium deficiency is usually caused by irregular watering. Water carries calcium and other nutrients throughout the plant, and without enough water, the calcium, which is being used first for foliar growth, doesn't make its way to the fruits.
Calcium is required in relatively large concentrations for normal cell growth, and when the rapidly-growing fruit is deprived of calcium the tissues break down, leaving the characteristic lesion.
Other factors that can reduce the uptake and movement of calcium into the plant include low calcium levels in the soil, excessive soil moisture, root damage, and a soil pH that is too high or too low below the optimum 6.5.
To control this problem, maintain even soil moisture by watering regularly. Amending the soil with organic matter such as compost will improve the soil's ability to retain water, and mulching around your tomatoes will reduce water evaporation from the soil.
Avoid heavy applications of high-nitrogen fertilizer, and if your soil is deficient in calcium, it can be amended with gypsum or another source of calcium. One easily available source of calcium happens to be eggshells, which are high in calcium carbonate, an excellent soil amendment. Incorporating crushed eggshells into the soil around tomato plants or at the bottom of their planting holes will help prevent blossom end rot.
UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system. To learn more about us and our upcoming events, and for help with gardening in our area visit our website. If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at 530-552-5812. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.
- Author: Help Desk Team
This post is a rerun from 2023.
Have you noticed tomatoes that have round, water-soaked spots on the bottom? Blossom end rot (BER) is a frustrating problem that can be quite common in vegetable gardens, as it can affect tomatoes, peppers, and squash. You might notice it after a few very hot days. It usually starts on green fruit as a small, discolored spot on the end opposite the stem that might look water soaked. The spot enlarges and tissues dry out, becoming sunken, collapsed, and leathery.
Some tomato varieties, especially paste tomatoes, are affected more than others, but all varieties except cherry tomatoes seem to be susceptible if conditions are conducive. It is more likely to occur earlier in the season when plants are rapidly growing, but it can also show up later in the season when we have hot, dry weather.
Blossom end rot results from a low level of calcium in the fruit and a lack of water balance in the plant. Most of our soils have plenty of available calcium so there is no need to add more. Fluctuations in irrigation and/or heavy application of nitrogen are often the culprits in this condition. To reduce blossom end rot, monitor soil moisture to make sure the root zone neither dries out nor remains saturated. Follow recommended rates for vegetable fertilizers, using organic fertilizers.
Improvement in irrigation practices usually results in the problem going away. Rather than watering on a schedule, you should check the soil to determine its moisture level. Either by digging down into the soil without disturbing the roots or using a moisture meter, check to make sure the entire root zone is moist but not soggy. Use mulch around the plants to help maintain soil moisture, but make sure the mulch isn't right against the base of the plants.
Blossom end rot is not caused by a pathogen, so there are no pesticide solutions.
To reduce blossom-end rot:
• Use cover crops in the off season to increase water-holding organic matter in the soil.
• Irrigate before periods of hot weather.
• Don't disturb the root area.
• Don't over fertilize. Too much nitrogen during the early fruiting period can tie up calcium and make BER worse. Manure, especially poultry manure, can make it worse.
Vegetables affected by blossom end rot are still edible if they haven't begun to get moldy. Just cut away the discolored area.
More information about blossom end rot:
http://ipm.ucanr.edu/PMG/GARDEN/VEGES/ENVIRON/blossomendrot.html
Information about growing tomatoes in the home garden: https://anrcatalog.ucanr.edu/pdf/8159.pdf
Help Desk of the UC Master Gardeners of Contra Costa County (SEH)
![Second photo of blossom end rot Second photo of blossom end rot](/blogs/blogcore/blogfiles/107575.jpg)
![Third photo of blossom end rot Third photo of blossom end rot](/blogs/blogcore/blogfiles/107576.jpg)
- Author: Help Desk Team
Have you noticed tomatoes that have round, water-soaked spots on the bottom? Blossom end rot (BER) is a frustrating problem that can be quite common in vegetable gardens, as it can affect tomatoes, peppers, and squash. You might notice it after a few very hot days. It usually starts on green fruit as a small, discolored spot on the end opposite the stem that might look water soaked. The spot enlarges and tissues dry out, becoming sunken, collapsed, and leathery.
Some tomato varieties, especially paste tomatoes, are affected more than others, but all varieties except cherry tomatoes seem to be susceptible if conditions are conducive. It is more likely to occur earlier in the season when plants are rapidly growing, but it can also show up later in the season when we have hot, dry weather.
Blossom end rot results from a low level of calcium in the fruit and a lack of water balance in the plant. Most of our soils have plenty of available calcium so there is no need to add more. Fluctuations in irrigation and/or heavy application of nitrogen are often the culprits in this condition. To reduce blossom end rot, monitor soil moisture to make sure the root zone neither dries out nor remains saturated. Follow recommended rates for vegetable fertilizers, using organic fertilizers.
Improvement in irrigation practices usually results in the problem going away. Rather than watering on a schedule, you should check the soil to determine its moisture level. Either by digging down into the soil without disturbing the roots or using a moisture meter, check to make sure the entire root zone is moist but not soggy. Use mulch around the plants to help maintain soil moisture, but make sure the mulch isn't right against the base of the plants.
Blossom end rot is not caused by a pathogen, so there are no pesticide solutions.
To reduce blossom-end rot:
• Use cover crops in the off season to increase water-holding organic matter in the soil.
• Irrigate before periods of hot weather.
• Don't disturb the root area.
• Don't over fertilize. Too much nitrogen during the early fruiting period can tie up calcium and make BER worse. Manure, especially poultry manure, can make it worse.
Vegetables affected by blossom end rot are still edible if they haven't begun to get moldy. Just cut away the discolored area.
More information about blossom end rot:
http://ipm.ucanr.edu/PMG/GARDEN/VEGES/ENVIRON/blossomendrot.html
Information about growing tomatoes in the home garden: https://anrcatalog.ucanr.edu/pdf/8159.pdf
Help Desk of the UC Master Gardeners of Contra Costa County (SEH)
![Photo of blossom end rot Photo of blossom end rot](/blogs/blogcore/blogfiles/100417.jpg)
![blossom end rot3-450 blossom end rot3-450](/blogs/blogcore/blogfiles/100419.jpg)
By T. Eric Nightingale, UC Master Gardener of Napa County
Spring is finally here and that means that tomato season is around the corner. Don't get too excited, though. Even though seedlings will be showing up in nurseries, it's best to wait to plant them.
Tomatoes need warm air and soil, as well as a lot of sunlight, to grow strong and healthy. Planting too early can leave them spindly and weak.
Should you want to be sure the time is right, test the soil temperature with a soil thermometer. It should be 60°F or more at a depth of two to three inches. Usually this occurs in early May.
Choosing a proper location for your tomato garden is important. The spot should get several hours of sunlight each day. You may have a prime spot but don't overuse it. Like other members of the nightshade family, tomatoes nurture the soil fungi Fusarium and Verticillium. The soil can become infected if tomatoes are planted in the same location too many years in a row. Rotating your tomato planting locations, or changing out the soil in a raised bed, will prevent the fungus from affecting your vegetables.
Plant tomatoes deeply. First, remove any leaves below the top eight inches. Place the seedling at a slight angle in the hole so that only the top eight inches sit about the hole. The plant's buried stem will push fresh roots, giving the young plant increased access to water and nutrients. Tomatoes also need a good deal of room to grow, so plant them at least two feet apart.
After your seedlings are all snug in their beds, they need some nurturing. If you are concerned about hungry animals or other threats, cover the tomatoes with the top half of a large soda bottle. Not only can this keep them from becoming someone's midnight snack, but it provides them with a personal greenhouse to keep them warm.
Tomatoes thrive with water, especially in the early days. Make sure to give them enough that the water soaks deep into the soil. This will ensure the plants get enough water immediately but will also encourage their roots to follow the water deep into the soil, helping the plants stay hydrated later.
As your plants grow, they will likely require support. Some tomatoes are “determinant” and grow into a shrub only a few feet tall. Many others are “indeterminate,” however, and will continue to grow like a vine until cold weather arrives.
For these motivated climbers you will need a tomato cage or other device. I have used a few stakes placed in a circle around the plant, with loose string or plant tape strung between them. This structure provides enough support while also allowing me to easily harvest the fruits of my labor.
Tomatoes can self-pollinate, so it's possible to get fruit while growing only one plant. The pollen still needs to move from one flower to the next, though. To be sure this happens, give your plants a light shake every morning. This jostling will knock some pollen airborne and help the process along.
One common disorder often seen on Roma or elongated tomatoes is blossom-end rot. You'll recognize the symptoms when you see fruit with an ugly brown sunken circle on one end. This condition can be caused by heavy applications of nitrogen fertilizer and extreme fluctuations in water supply. To avoid this problem always use a fertilizer with balanced amount of nitrogen and phosphorus and provide regular deep watering. Use a mulch around the base of the plants to reduce the loss of moisture from the soil.
Healthy transplants should not need much fertilizing until flowering and fruit set begins, too much nitrogen will give vigorous leaf growth delay flowering. Use a balanced fertilizer to grow healthy tomatoes, Nitrogen, is the nutrient responsible for leaf and stem growth and phosphorus for bud development. Fertilize every 4-6 weeks following the instructions on the label. Avoid applying more than is need so extra fertilizer doesn't leach beyond the root zone and
into the ground water.
Experiment and find what practices work best in your garden. With hard work and a little luck, you will be on the path to a bountiful harvest.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County (http:/napamg.ucanr.edu) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
- Author: Lauren Snowden
- Editor: Melissa G. Womack
Tomatoes are so popular with home gardeners, that a 2014 study by the National Gardening Association showed that 86 percent of homes with vegetable gardens grow tomatoes! It's 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 (4.5 to 6.8 kg) 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 abiotic disorders, diseases or pests. Abiotic disorders result from nonliving causes and are oftentimes environmental, for example: unfavorable soil conditions, too much or too little water, temperature extremes, physical or chemical injuries, and other issues that can harm or kill a plant. 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.
1. Sunburn
![Sunscald damage. (UC Statewide IPM Project) Sunscald damage. (UC Statewide IPM Project)](http://ucanr.edu/blogs/UCIPMurbanpests/blogfiles/44656.jpg)
Problem: Fruit turns light brown and leathery on side exposed to sun.
Cause: Overexposure to sunlight.
Solutions:
• Maintain plant vigor to produce adequate leaf cover.
• Avoid overpruning.
• Provide partial shade during hours of most intense sunlight.
2. Leaf Roll
Problem: Older leaves roll upward and inward suddenly, leaves become stiff to the touch, brittle, and leathery.
Causes: High light intensity and high soil moisture, particularly when plants are staked and heavily pruned
Solution:
• Choose less-susceptible varieties.
• Maintain even soil moisture.
• Provide shade during hours of intense sunlight.
3. 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.
Causes: Calcium nutrition and water balance in the plant, aggravated by high soil salt content and fluctuating soil moisture.
Solutions:
• Maintain even soil moisture.
• Amend planting area with compost to improve water retention.
• Avoid heavy applications of high-nitrogen fertilizer.
• Soils deficient in calcium may be amended with gypsum.
4. Fruit Cracks and Catfacing
Problem: Circular concentric cracks around the stem end (concentric cracking), cracks radiating outward from the stem (radial cracking), malformation and cracking at the blossom end (catfacing).
Causes: Very fast growth with high temperatures and high soil moisture levels. Wide fluctuation in soil moisture and or air temperature. Any disturbances to flower parts during blossoming.
Solution:
• Keep soil evenly moist.
• Maintain good leaf cover or provide partial shade during hours of most intense sunlight.
• Mulch around the plant 3 to 7 inches deep to maintain soil moisture and temperature.
5. Solar Yellowing and Green Shoulders
Problem: Yellow or yellow-orange instead of normal red color, upper portions of the fruit remain green even though the lower portion appears red and ripe.
Cause: High temperatures and high light intensity.
Solutions:
• Maintian plant vigor to produce adequate leaf cover.
• Avoid overpruning.
• Provide partial shade during hours of most intense sunlight.
Pests eating your tomatoes?
Other damage to tomato plants can be caused by a variety of pests. Some examples include: hornworms, tomato fruitworms, tomato pinworms, stink bugs, white flies, and leafminers. For information about other pests on tomatoes, visit the UC IPM Tomato Page. For general help identifying and managing pests in your garden, visit the UC IPM website.
Need free gardening advice?
Since 1981, the UC Master Gardener Program has been extending UC research based information about home horticulture, sustainable landscape, and pest management practices to the public. Through a vast network of more than 6,000 certified UC Master Gardener volunteers, the program is administered by local UC Cooperative Extension (UCCE) county offices across California. Contact the UC Master Gardener Program in your county for more information about edible gardening or upcoming educational workshops, mg.ucanr.edu
Originally posted on the UC Master Gardener Statewide Blog.