Xtremehorticulture

Calcium Deficiency of Tomato and Blossom End Rot

Q. I wanted to ask about a strange occurrence in my tomato garden. Not all, but some of my tomatoes when they ripen, have these black spots only at the bottom of the tomato crop. I just wanted to reach out and see if you could tell me about what causes or could be causing the discoloration? Blossom end rot of tomato Blossom end rot of pepper A. That is normally a physiological problem on tomatoes, peppers and some eggplant this time of year called blossom end rot. Some scientists claim it is caused by an imbalance of calcium in some of the fruit when soils are cooler. Sometimes calcium sprays can fix it. Some varieties of tomatoes show this problem more than others. This imbalance of calcium in other plants is called “bitter pit” in susceptible apples like ‘Mutsu’ and “corky spot” in susceptible pears like ‘Comice’. Bitter pit of ‘Pink Lady’ apple Corky spot of  ‘Comice’ pear             Apples and pears take regular leaf sprays of calcium as a temporary fix in them. The easiest way to fix this problem in tomatoes is to use a less susceptible variety to blossom end rot. Otherwise, it may take several sprays of a liquid calcium spray (such as calcium chloride or calcium sulfate mixed in water) to fix it. The fruit is okay to eat, it just looks odd.

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Are Pears with Corky Spot Edible?

Q. I was reading your blog about the brown spots in the flesh of pears. Is fruit with these spots edible?   Keiffer pear with outside evidence of Corky spot With the small green dimple in the center of the fruit A. Corky spot in pears appears as brown areas, about the size of a small marble or smaller, in the flesh of the fruit. These spots are surrounded by healthy flesh. On the outside skin it is hard to see but often it is slightly sunken and frequently some green remains after the fruit ripens.             The flesh is not rotten. The cells in the flesh do not have enough calcium for good development and they die and are brown. These spots do not taste good and are usually dry. But if you eat them it’s not a problem and will not harm you. Corky spot on the interior flesh of Keiffer pear.             My experience with this “disease” is that it develops on pears grown on older trees, usually over ten years of age. I theorize that the roots of the tree have exhausted the calcium in the soil surrounding them. The soil is full of calcium, but it cannot release it fast enough as the fruit develop. Corky spot on Comice pear growing in the Mojave Desert             What to do? Applications of calcium to the soil are not 100% effective. It is recommended that the fruit on the tree is sprayed with a liquid calcium solution as the fruit is enlarging. The most effective sprays are made with 5% calcium chloride dissolved in water. The calcium chloride should be food grade. 5% solution of Foodgrade calcium chloride will work as a foliar spray. This foodgrade calcium chloride is for homebrewing             These spray applications are made five times, at least a week apart, as the fruit enlarges. Direct the sprays mostly at the fruit. Leaf sprays are less important.             Not all pears are affected equally. Some pears appear to handle low soil calcium levels better than others. The problem may also vary with different types of soils. Watch for it on older pear trees.             By the way, this disorder also affects some apples. When it does, it is no longer called “Corky Spot” but “Bitter Pit” instead.

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Brown Spots in Pear and Apple Flesh Could be Lack of Calcium

Do you have an apple or pear tree that is about 10 or 12 years old, giving you delicious looking fruit ball when you bite or cut into the fruit, you see corky, brown spots in the flesh? If you do, this could be a sign that your fruit trees will need to be sprayed with calcium when the fruit is young and during its formation. Corky spot in Keiffer pear This disorder is called bitter pit in apple but called corky spot when it occurs in pear. The root of the problem is the same; not enough calcium getting from the soil to the developing fruit. Established fruit trees take a lot of nutrients out of the soil each year for the developing fruit. It would seem unlikely in our desert soils that are full of calcium that a lack of calcium would be a problem. But it can be. Established fruit trees continually mine nutrients from the same areas of the soil each year. Once a tree becomes established where irrigations are limited to a certain area, the root systems do not continue to explore the surrounding soil. They continue to mine these elements where they are. Corky spot in Comice pear Calcium is relatively insoluble. In other words, even though there is plenty of this element in the soil it does not easily dissolve into the applied water before it is taken up by the plant. Producing fruit, and a lot of it, draws heavily on the supply of calcium the tree can find in the soil. Over years the available calcium supply diminishes. If the soil does not allow calcium to dissolve when the plant needs it, calcium deficiencies occur. If you look closely at the fruit there can be telltale indicators that bitter pit or corky spot is present without cutting into the fruit. I look for dimples in the skin. If you look closely at these dimples you will see that they do not “ripen” or turn from green to its mature color like the rest of the skin. If you don’t look closely, you will miss it. Greenish dimples on the surface of the fruit can be a dead giveaway that corky spot or bitter pit has affected the fruit. Cutting the dimple away will expose the corky spot just under the surface. Normally this calcium deficiency occurs on some apples and some pairs but it is less likely on others. In our climate in the Las Vegas Valley I have seen it develop on Mutsu apple and Anjou, Comice and Keiffer pears. To remedy the problem you will need to spray on the fruit as it is developing, calcium sprays. I usually buy food-grade or aquarium-grade calcium chloride. I dissolve about 3-5 pounds of calcium chloride in 100 gallons of water. To convert, there is 16 ounces or 454 grams in one pound. Dissolve the calcium chloride thoroughly in warm water and add a liquid detergent or some sort of spreading agent to help the calcium entry through the skin of the fruit. Spray on the fruit as soon as you see the fruit beginning to develop. Make five applications of the spray about one week apart. Avoid spraying when temperatures are high. Spray in the early morning hours. Real wedding the fruit lightly with pure water after the spray has dried will help more of the calcium to enter the fruit. These five applications of calcium chloride applied along with a sticker/spreader when the fruit is still young will help to prevent bitter pit or corky spot from developing.

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When Do You Pick Bartlett Pear?

 Bartlett pear. The pear on the left is ready for picking. Notice the skin color change from green (right) to yellowish green. Notice also the seeds in the pear on the left are brown. The one on the right is still white. Q. Just this year planted a Bartlett pear, and a Comice for a pollinator. Both have pears on them now. But I thought Bartletts were supposed to ripen in August. I picked one of my four pears, chilled it in the refrigerator for a couple days, then let it sit for about three more days before slicing it. It remained hard as a golf ball and no tastier. When are they supposed to be ripe?    A. Bartletts are picked when the color of the pear turns from green to a yellowish green but still hard. Then you must put it at room temperature to continue ripening and turn soft and buttery. If you let them soften on the tree, which you did not do, the flesh will be gritty with all those stone cells in the flesh. Corky spot on Comice pear If you pick just as the outside skin turns color to light or yellowish green, the flesh has more of a buttery texture. The pear on the left is the right color for picking. Also, the seeds should be brown inside when ready to pick. We are not picking Bartlett until mid September. Just an aside, Bartlett usually does not need a pollinator in most of the Western United States. It does in other parts of the country. Also, be aware that Comice tends to get corky spot in our alkaline soils and may require foliar calcium sprays to correct that.

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