Black rotten spots on bottom of fruit?
 

Hi! This is my first attempt at growing tomatoes and I've had to throw out 3 already due to black, rotten spots on the bottom of the fruit. The plant is a big beef hybrid and is planted in moisture control potting soil. It gets about 5 hours of hot sunlight a day and I give it 56 oz of water a day. There were some bugs on the plant a couple of weeks ago, so I used a popular pesticide dust, but I am still getting black spots on the new fruits. Am I watering too much or is this caused by a bug or a disease? Thanks!

It's probably blossom end rot (BER) which in my limited understanding can be caused partly/made worse by uneven watering. It's usually more common in early fruits and in paste types.
Maybe someone in your area can comment more specifically about the moisture control mix/56 oz. of water/day combo. I don't grow in containers but the combination seems like a lot of moisture to me- then again I don't know TX heat either.
BER isn't caused by a bug and I don't think it's technically a disease either.

watering fluctuations can be a factor but so can calcium. When you pot up container tomatoes you usually want to mix in some lime. If you have a hydroponics store near you I would recommend you pick up a cal/mag supplement and follow the package directions. I personally use 1 tbs molasses per a gallon of water and use that as it contains calcium, magnesium, iron, and some trace elements.

Either one should help fix the BER issues. Though I am sure some others will also have other alternative treatments that will also work equally as well.

Blossom-End Rot (BER) summary (with picture):
[url]http://ohioline.osu.edu/hyg-fact/3000/3117.html[/url]

This says foliar calcium sprays are mostly useless. Other people
do that every year. It could be that a foliar spray saturates the leaves
with calcium, so that what is taken up by the roots is more available
to the fruit, reducing BER. It could also be that the simple act of spraying
itself cools the plant, and that may have some effect on BER (less demand
for water from the leaves allows calcium that is absorbed by the roots
to go elsewhere, like to developing fruit).

One thing is sure: the calcium needs to be in the soil or container media
(hence the lime, dolomite lime, or gypsum added), and the soil needs to
be moist for the calcium to be available to the plant. Growers in very hot
climates have sometimes found that more water fixes it (their soil
perhaps drains well and is simply drying out faster than they expected).
Growers in cooler climates sometimes find that more water makes it
worse (no idea why).

Many of us struggle with BER from water issues, even in soils with
plenty of calcium. A dry stretch followed by heavy rain can bring it
on (splitting fruit, too). It is often an unpleasant result of fluctuating
moisture levels. It seems to be more common in plants with roma
type fruits. Sometimes you see it mostly on the first fruits early in
the season on a plant that grows out of it.

Thanks for the tips! It is definitely BER so I will head to the store to get the supplements!

For future reference you may want to avoid MG Moisture Control potting mix for container tomatoes. I used it one year in one of my containers and found it retained too much moisture. I now use MG regular potting mix exclusively for container tomatoes. It's a bit cheaper and I've never had problems with it.

I find a tool like this handy to check moisture levels in containers
before I water:
[url]http://www.amazon.com/Luster-Leaf-1810-Rapitest-Moisture/dp/B001B2WALI/ref=sr_1_5?s=home-garden&ie=UTF8&qid=1307415011&sr=1-5[/url]

[QUOTE=kwselke;217612]For future reference you may want to avoid MG Moisture Control potting mix for container tomatoes. I used it one year in one of my containers and found it retained too much moisture. I now use MG regular potting mix exclusively for container tomatoes. It's a bit cheaper and I've never had problems with it.[/QUOTE]

I agree used it two years ago and never would use again I keep seeing the comercials advertising it and it is so bad for tomatoes I am sure it is not good for anything other than maybe a hanging basket.

Craig