- Author: Ed Perry
Symptoms of Blossom-End Rot
The first symptom is usually the appearance of a small spot at or near the blossom scar of green fruits. As the spot enlarges, the affected tissues dry out and become light brown to dark brown. The area then develops into a well defined sunken spot, with the tissues collapsed and leathery. The spot can grow large enough to cover the entire bottom half of the fruit. The skin remains unbroken because it is the tissues beneath that have dried out and collapsed. The disorder not only affects tomatoes, but can also occur on peppers and squash. While the fruit looks unappetizing, you can still eat it - just cut out the affected part.
Causes of Blossom-End Rot
Tips for Preventing Blossom-End Rot
There are several things you can do to prevent the calcium deficiency, and blossom end rot. First, water deeply, and on a regular schedule, especially during hot weather. Use a soil-covering mulch around your plants to conserve moisture, especially if your soil is sandy. If you are growing tomatoes in containers filled with a porous potting soil, you may need to water the plants every day during hot periods. When cultivation is necessary, it should not be too near
the plants nor too deep, so that valuable water absorbing roots remain uninjured and viable. The best way of preventing the disorder is to maintain adequate and uniform soil moisture in the root zone throughout the growing season.
More Questions about Vegetables?
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References
UC IPM http://ipm.ucanr.edu/PMG/GARDEN/VEGES/ENVIRON/blossomendrot.html
Ed Perry is the emeritus Environmental Horticultural Advisor for University of California Cooperative Extension (UCCE) in Stanislaus County where he worked for over 30 years.
/h3>/h3>/h3>/h3>/h3>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: Ben Faber
Another impact of the drought? There have been reports of a sunken, leathery patch around the blossom end (opposite of the stem end) of citrus fruit. This has been reported on lemons, limes and mandarins, but I am sure growers are seeing it on oranges, as well as other citrus relatives. This is an abiotic problem caused by a lack of calcium to the fruit, a problem with the plant's growing conditions, not a disease. This is a serious disorder found in various fruits and vegetables, such as tomatoes, melons, peppers and eggplants
Blossom-end rot begins as small tan, water soaked lesions on the blossom end of the fruit. The lesion enlarges and becomes sunken, dark, and leathery. On peppers, the lesion is more commonly found on the side of the fruit towards the blossom end. Also, on peppers it can be sometimes confused with sun scald. Fruit infected by blossom-end rot ripen often become infected with secondary organisms such as Alternaria spp (most likely the surrounding tissue in the photo below).
This is a physiological disorder of low calcium in the fruit. Calcium is required for normal cell growth and in relatively high concentration for new tissue growth. Rapidly growing fruit will begin to breakdown at the blossom end because that is the last place of the fruit tissue to receive calcium and also the area with the lowest concentration of calcium.
In rapidly growing plants, calcium cannot move to those rapidly growing areas quickly enough. Because calcium moves with water, fluctuations in water supply can cause blossom-end rot. Large fluctuations in soil moisture inhibit uptake and movement of calcium within the plant. Excessive nitrogen promotes rapid plant growth, which can cause low concentrations of calcium to occur in plant tissue. Leaf tissue can often not disclose a low calcium in fruit because of the lag in movement of calcium to the rapidly growing fruit tissue.
Other causes such as low calcium levels in the soil or high amounts of cations in the soil which compete with calcium uptake can also cause blossom-end rot. This is especially true in areas of soils derived from serpentine rock that are high in magnesium. The magnesium competes with calcium uptake.
Proper fertilization and water management help to minimize this problem. Avoid over fertilizing the crop. Also avoid allowing the soil to become too dry and then overly wet. Wide fluctuations in soil moisture inhibit calcium uptake and movement. If calcium is deficient or high salts occur in the soil, gypsum applications can help, but delayed uptake may not help fruit tissue content. Often, foliar applications of calcium may be beneficial.
- Author: Mark Bolda
Great article here by Dr. Robert Mikkelson from the International Plant Nutrition Institute concerning the why and how of liming a soil which is acidic.
Here's the short of it:
Several factors contribute to the acidity of a soil, one being the geologic composition of the base material, another being lots of rain which leaches out calcium and magnesium. Another contributing factor to soil acidity in agricultural soils is the continual use of nitrogen fertilizers, especially in the same spot over a longer period of time. Both urea and ammonium, when converted to nitrate by soil micro-organisms, release hydrogen ions, the higher the concentration of which raise the acidity of the soil.
A common grower solution to acidic soils is the addition of ground limestone. However, while limestone neutralizes acidity, adds calcium and enhances the solubility of phosphate (and consequently availability of phosphorous to the the plant) does not dissolve well at all at pH's above 6.5 (common for soils of the Central Coast) and one would be hard put to realize the aforementioned benefits at this pH. So if one needs to add calcium to a soil with a pH above 6.5, the better choice would be gypsum, which while it also does not dissolve well in a neutral pH soil, does supply more soluble calcium.
/span>- Author: Ben Faber
With the drought our perpetual salt problems are exacerbated due to less water and often more saline water. The question keeps coming up if gypsum (calcium sulfate) can help correct the problem. And the answer is maybe, but along the coast, probably not. The problem there is confusion about what is a saline soil and what is a sodic soil. A saline soil is one that is dominated by salts, but has a pH below 8.5 and can have a white crust that will actually taste salty. A sodic soil is one dominated by sodium, has a pH above 8.5 and can be saline, as well. Often though, there is a brownish cast to the surface salt crust. This is caused by dispersion (dissolved) of soil organic matter caused by the high pH. It's like cooking with vinegar when you make ceviche out of fish. Saline soils often have a high calcium content and may have sodium, but at a very low ratio compared to calcium. Most of the sodic soils in California are found in the Central and Imperial Valleys. Along the coast, the soils, if they have a problem, are largely saline.
The way gypsum works, is that the added calcium displaces soil sodium, pushing it lower in the soil column. The process also requires a lot of water to move the sodium through the soil column.
So the answer is, along the coast, gypsum is unlikely to improve soil conditions. However, there are other instances where it might help. In the San Luis Obispo area there are lots of serpentine derived soils that have a high magnesium content relative to calcium. And they commonly aren't saline, just an imbalance between the two cations. This can lead to infiltration problems and calcium deficiency in plants. Apples are especially sensitive to this high Mg:Ca ratio and develop a condition called “bitter pit”, a surface, brown pitting in the skin. There are other crops, like celery that are especially sensitive, but even avocado can be mildly affected. In the case of magnesium imbalance, gypsum can help.