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.
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.
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| 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.
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.
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.
.JPG) |
| 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.
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.
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.
.JPG) |
| 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.
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.
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.
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.
the fruit is still young will help to prevent bitter pit or corky spot from
developing.
I also have a Bartlett pear tree and have the same spotting in the fruit. If I put calcuim in the soil now to soak in over the winter rains, will this remedy as much as your suggestion of spraying?
Not really. There is usually plenty of calcium in the soil when this occurs. It's not a problem of a lack of calcium in the soil. It's a problem that the plant can no longer take enough calcium from the soil to satisfy its needs. All plans, including fruits and vegetables have an enormous amount of calcium in them.When fruit trees are planted in soils with lots of calcium, the calcium present in the soil as either lime (calcium carbonate) or other calcium minerals cannot dissolve fast enough to meet the high demand of those plants for calcium. We harvest fruit and vegetables from the soils, basically removing the calcium, and the soil must dissolve more calcium filled minerals to replace what is lost. So just adding a calcium mineral will not work. In cases like this we have to spray the tree (aimed mostly at the fruit) with a calcium solution as the fruit is getting larger. This usually requires about five spray applications during the growing season starting when the fruit is first developing, quite small. The most effective solution sprayed on the fruit is calcium chloride. This spray solution should include a surfactant to help move the calcium inside the fruit rather than just run off the surface. You can use about 1 1/2 ounces per gallon of spray of a standard spray surfactant that you can purchase called a "wetting agent" or use a highly refined detergent such as a Castille-type soap. It will probably cost about the same.
Is fruit w/spots edible? What if I can’t do 5 consecutive weekly sprays? My problem Kiefer is at second home do not usually there that long at a time
The fruit is edible. No problem there. It is just not pretty.
It is important to "feed" the fruit calcium as it is getting bigger. That is when it is running out. If you can get on sprays during this time you will reduce the calcium deficiency. The earlier when fruit is enlarging…the better.