Blossom-end rot can not be stopped or reversed on the individual tomatoes it affects. However, adjusting the calcium levels of the soil, maintaining consistent moisture, and addressing other environmental factors can allow the next round of fruits to remain flawless.
Blossom end rot is caused by a calcium deficiency in developing fruit. Fluctuating soil moisture due to overwatering or drought, high nitrogen fertilization, and root pruning during cultivation are conducive to blossom end rot.
Unfortunately, once a tomato has blossom end rot, it won't go away. However, you can still save the plant and any remaining tomatoes it produces. Put all rotten tomatoes in your compost and cut your losses.
And to answer your second question: Yes you can cut off the rot and eat what's left of the fruit — it won't kill you or make you sick. However, I find that the remaining fruit tends to be mealy and poor quality. If you do eat it, do so right away; do not try to can or preserve it.
Foliar Spray
Commercial foliar calcium sprays (calcium acetate, calcium nitrate, and calcium chloride) are the quickest remedy for acute calcium deficiency, as plants absorb nutrients more efficiently through leaves than through roots.
The first sign you'll see are tiny, water-soaked patches that look like bruises on the bottom of the fruit or vegetable. Over time, the spot becomes darker and turns brown with sunken patches. Once the blossom end rot spot gets bigger, you'll notice it turns a darker brown to black, often as a leather-like texture.
Baking soda isn't a good solution for preventing blossom end rot. If your soil pH levels are low and affecting the tomato plant's ability to absorb calcium, adding this kitchen pantry staple might raise them. However, this will be a temporary effect, and the amount you might need to use could harm your plant's health.
Also, add crumbled egg shells to your compost or bury them in your garden over time to help maintain the calcium levels. Fertilize wisely. Use a fertilizer at planting time that contains calcium, such as Miracle-Gro® Shake 'n Feed® Tomato, Fruit & Vegetable Plant Food.
Pick off any affected fruits because they will not recover and will only drain moisture and calcium needed by healthy fruit. It is safe to eat the undamaged parts of fruits with Blossom End Rot. Merely cut away the blackened part.
If you experience several days of cold soil temps and are concerned about the reoccurrence of blossom end rot, it is best to find a very soluble Ca form. One of your best options is called Calcium Nitrate.
Carefully lift the plant from its pot and brush away as much potting mix from the plant's roots as possible. Then, rinse the roots to remove the rest of the old potting mix and assess the damage. Plants with moderate root rot often improve with treatment. However, if root rot is severe, the plant may not recover.
Tomatoes & Epsom Salt
As the tomato plant matures, you can work in one tablespoon of Ultra Epsom Salt per foot of plant height around the base of each tomato plant, or use the tank sprayer solution previously mentioned and spray plants every two weeks.
Ammoniacal nitrogen may increase blossom-end rot as excess ammonium ions reduce calcium uptake. Avoid over-fertilization as side dressings during early fruiting, especially with ammoniacal forms of nitrogen (Miracle-Gro, Miracle-Gro Potting Soils, Osmocote, etc., read the ingredients on the package).
How can I control blossom end rot? Avoid conditions where there is too much or too little water. Water evenly and mulch the soil to retain moisture during dry periods. Avoid practices that would damage roots (e.g., cultivating too near plants thereby cutting roots).
The same properties that make milk good for a human, such as the calcium and B vitamins, are what benefits plants. The calcium helps the plants grow, as well as prevent blossom end rot, which can be caused by a calcium deficiency. This condition is common in tomato, peppers, and squash plants.
Adding too much calcium to your soil could kill your plants because it raised the soil pH to levels that plants cannot stand.
Using Lime/Calcium to Treat Blossom End Rot on Tomatoes How to stop and prevent Blossom End Rot on tomatoes. They key is to make sure your plants have calcium and even watering. Lime is a great source of calcium - with Gary Pilarchik.
Sprinkle a little less than ¼ cup of ARM & HAMMER™ Baking Soda around one of the tomato plant seedlings and mark it with a stake tag. Water and tend to your tomato plants as they grow. Sprinkle a little more ARM & HAMMER™ Baking Soda on the soil after the plan is half grown.
You shouldn't eat the spots of blossom-end rot, but the rest of the tomato is still edible. "Keep in mind that if progressed enough, it will rot the tomato inside," says Root. "If caught early enough, it usually is just an unsightly blemish that can be cut away."
While lime benefits tomatoes in a few crucial ways, it can cause harm if you use too much. Raising the pH beyond 6.8 may prevent the tomato plant from absorbing magnesium, a mineral vital to photosynthesis.
Symptoms of calcium deficiency include stunted plant growth, leaf curling, dark leaf veins, weakened plants, and blossom-end rot in fruits. Fruit plants like tomatoes and peppers may develop dark, sunken areas in the fruit.