[Market-farming] blossom end rot

Liz Pike liz at laughingbrookfarm.com
Fri May 9 09:37:23 EDT 2003

Hey Joan, I dreamed about BER all night.

The reason I asked is I'm working on an article for the website on
trellising tomatoes.  In my research, I've come across umpteen sources that
quote the statement, "Trellising increases the incidence of BER," which made
me scratch my head because I've always believed BER is caused by a lack of
calcium.  Boost the calcium, bye-bye BER.  How can trellising effect calcium
in the soil??

Well, not so fast.  Come to find out it's caused by several factors, and the
only way to determine which factor is causing your BER is to work through
the list.

Trellising in & of itself does not cause BER.  Trellising DOES disturb the
roots, which sets up a domino effect of cutting off water intake to the
plant, which cuts off calcium absorption.  Since so much water is transpired
from the leaves, thus a loss of calcium for the fruit, more calcium must be
applied...if that's the cause.

(Forgive me Bill Shoemaker for explaining this in my layman's terms!!)

But the most important thing I learned, BER can also be caused by several
things that inhibit consistent water flow, hence calcium availability to the
fruit.  Excessive salts in the ground (too much fertilizer), hot weather,
variable water supply (uneven irrigation, drought, too much water ((roots
standing in water)), etc), disturbing the roots when cultivating, pruning,
or even the variety of tomato--some are more predisposed to having it.

So, even though supplying enough calcium is important, regulating moisture,
so the calcium can be utilized by the plant is just as important.

As for the boron, I don't know about that.

Joel Gruver, soil scientist with NC State told me applying gypsum, which is
organic allowable, at a rate of 300 lbs per acre (assuming avg 4300 plants
per acre), or 7 lbs per hundred plants will supply all the calcium needs of
the tomato if that's lacking.  A soil test will confirm if that's needed.

Liz Pike
Laughingbrook Farm
Westfield NC

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