[Arid_gardener] blossom end rot in tomatoes

[Janet Howe]

Original question:

Suzanne Douglass
85256
suzannedouglass at trappings-az.com

Why do my tomatoes have a large brown spot on the bottom of the fruit?


Answer:


Suzanne, your tomatoes are suffering from blossom end rot.  This
condition occurs under conditions of high plant water stress and heavy
fruit load. Hot, windy conditions with low relative humidity can cause
high transpiration rates ideal for inducing blossom end rot. 

The first year I grew tomatoes here in the desert I had the same
problem.  However, careful monitoring of water levels and heavy mulching
virtually eliminated the problem.  Tomatoes love moisture, but the soil
should be well draining with lots of organic matter and the heavy mulch
(3-4") will help to keep the soil from drying out too quickly and help
maintain a more constant moisture level.  I add organic matter each year
to the soil before planting, then after planting, I use a soaker hose
and then add the 3-4" of mulch over the top of the soaker hose.  Make
sure the mulch stays a few inches away from the plant itself, you don't
want the mulch to touch the stem of the plant.  

Your tomatoes already suffering from blossom end rot will not recover,
however, if you are growing indeterminate tomatoes, by correcting the
water levels, subsequent tomatoes should be fine.  Good luck!

Janet Howe
Master Gardener volunteer
University of Arizona Cooperative Extension