Garden Q&A: Blossom end rot a calcium deficiency
Question: My tomatoes are ripe on the top, but they are rotten on the bottom ends. What is happening?
Answer: I believe your tomatoes are suffering from one of two possible issues: blossom end rot or a fungal disease. Because we've had such a wet season, I suspect the latter may be the issue, but I will describe both and allow you to determine which you think is the probable culprit based on my description.
Blossom end rot is an affliction that begins as a small sunken canker at the bottom of the fruit and quickly develops into a large, sunken, black lesion. Unlike disease issues, blossom end rot is not caused by a bacteria or fungus, nor is it something that is caused by an insect pest, despite what many people commonly think. It is a disorder caused by a lack of calcium in the developing fruit.
During the growing season, tomatoes develop at a very rapid rate, and they use a lot of calcium in the growing process. When there is not enough calcium present, the fruit tissue breaks down into the sunken lesion you see at the bottom. Many times this lack of calcium is not caused by an actual soil deficiency, but rather by inconsistent watering.
Because calcium moves into a plant via water, if the plants are allowed to dry out between waterings, a calcium deficiency is the result. Blossom end rot is especially common in container-grown tomatoes or during years of inconsistent rainfall.
The reason I suspect blossom end rot is not the issue is because we've had plenty of consistent rainfall this summer. In fact, the frequent rains that have occurred throughout the growing season are creating the perfect recipe for many fungal and bacterial diseases.
And so, without seeing the fruits, my guess would be that your tomatoes have developed one of several common fungal issues. My tomatoes, and the tomatoes of many other local gardeners, are suffering from various bacterial and fungal blights and leaf spot issues. At this point in the season, there really isn't much you can do about them. Organic fungicides based on Bacillus subtilis (Serenade) or copper are an option, but when things are this wet, there is little we can do.
To help stave off fungal issues in future years, there are some cultural practices every gardener should be following each and every season:
• Always rotate your crops. If possible, do not plant tomatoes in the same place year after year. Some fungal spores can overwinter in the soil.
• Space plants properly to allow for plenty of air circulation. Fungal spores love wet conditions.
• When irrigating, try to keep the foliage as dry as possible.
• Some diseases are soil-borne. To keep the spores from splashing up onto the leaves, mulch the plants immediately after planting. Use a 2- to 3-inch layer of compost, straw or hay to mulch them.
• Avoid over-fertilization, especially the chemical kind. Tomato plants fed excessive amounts of fertilizer produce lots of green growth that crowds the fruits and traps humidity against them, encouraging fungal diseases to take hold.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio. Her website is www.jessicawalliser.com.
Send your gardening or landscaping questions to email@example.com or The Good Earth, 503 Martindale St., 3rd Floor, D.L. Clark Building, Pittsburgh, PA 15212.
Show commenting policy
TribLive commenting policy
You are solely responsible for your comments and by using TribLive.com you agree to our Terms of Service.
We moderate comments. Our goal is to provide substantive commentary for a general readership. By screening submissions, we provide a space where readers can share intelligent and informed commentary that enhances the quality of our news and information.
While most comments will be posted if they are on-topic and not abusive, moderating decisions are subjective. We will make them as carefully and consistently as we can. Because of the volume of reader comments, we cannot review individual moderation decisions with readers.
We value thoughtful comments representing a range of views that make their point quickly and politely. We make an effort to protect discussions from repeated comments either by the same reader or different readers.
We follow the same standards for taste as the daily newspaper. A few things we won't tolerate: personal attacks, obscenity, vulgarity, profanity (including expletives and letters followed by dashes), commercial promotion, impersonations, incoherence, proselytizing and SHOUTING. Don't include URLs to Web sites.
We do not edit comments. They are either approved or deleted. We reserve the right to edit a comment that is quoted or excerpted in an article. In this case, we may fix spelling and punctuation.
We welcome strong opinions and criticism of our work, but we don't want comments to become bogged down with discussions of our policies and we will moderate accordingly.
We appreciate it when readers and people quoted in articles or blog posts point out errors of fact or emphasis and will investigate all assertions. But these suggestions should be sent via e-mail. To avoid distracting other readers, we won't publish comments that suggest a correction. Instead, corrections will be made in a blog post or in an article.
- Nearing season’s midpoint, Steelers still have issues to sort out
- Ross brothers ordered to pay fine, remove debris from Christmas display
- Rossi: Fleury is, and will remain, Penguins’ soul
- Police seize phones of some Norwin High School students
- Injured Pitt center Rowell plays well-rounded role on campus
- Testing legs, giving backup goalie a chance are Penguins’ priorities
- Steelers film session: Watt kept under control
- 7 in custody after New Kensington drug raid
- Rostraver woman victim of home invasion
- 2 stores robbed in Alle-Kiski Valley
- Penguins notebook: Newcomers get 1st taste of rivalry with Flyers