In article ,
"David Hare-Scott" wrote:
The Henchman wrote:
I'm in Southern Ontario Zone 5b (Niagara escarpment)
I have tomatoes in pots, two plants per pot, staked. Pots are 12" x
12" x 12" deep. A bit of a gravel bed on the bottom, maybe 3/4"
thick. They face south and get 7 hours of sun a day. Soil is
triple mix topsoil with 1/3 peat moss, and drainage holes at bottom
of pots. These plants were planted by children in a school then we
inherited the plants when school was out for summer. They flowered
nice.
The bottoms of some of the tomatoes have gone black. A quick Google
search suggests this is prolly due to lack of calcium but we have 25
hardness hard water. Our garden water is not run thru the water
softener.
How can I determine if it's calcium defiency or not? What other
possibilities can this be? The leaves never wilt and growth and
foliage seem healthy. No bugs are eating the leaves. I've never
grown tomotes before. Our herb gardens and flower beds are fantastic
and are watered at the same intervals as our tomatoes.
If somebody wants pictures I can through up on the net if so.
Blossom end rot is a complex problem. Some highly qualified authorities are
not sure exactly how it happens although they seem to agree it is related to
calcium nutrition. There was a long thread on this at rec.gardens a week or
two ago. To summarise:
- BER is an issue with calcium mobility which occurs most often when the
plants are young and growing quickly. It often goes away without
intervention as the plants mature.
- It can be caused by lack of calcium in the soil or uneven watering which
can interfere with nutrient mobility.
- Some cultivars are more susceptible to it than others.
- If adding lime to supply calcium do not overdose as this may raise the pH
too far which will cause other nutrition problems.
David
Please allow me to obscure this explanation.
http://aob.oxfordjournals.org/cgi/content/full/95/4/571
"The symptoms, occurrence and search for the cause of blossom-end rot
(BER) in tomato (Lycopersicon esculentum) have been described frequently
in the scientific literature of the last century (see Brooks, 1914;
Spurr, 1959; Saure, 2001). The majority of studies have identified a
local Ca deficiency in the distal fruit tissue as the primary cause of
BER (Lyon et al., 1942; Ward, 1973; Bradfield and Guttridge, 1984; Adams
and Ho, 1992). For this reason, BER was considered to be a symptom of a
Ca-related physiological disorder (see Shear, 1975; Bangerth, 1979;
Kinet and Peet, 1997). However, the induction of BER in modern
glasshouse tomato production is rarely caused by insufficient Ca in the
feed. More often, BER occurs in plants with an adequate Ca supply when
grown under conditions that either (a) reduce the transport of Ca to
rapidly growing distal fruit tissue or (b) increase the demand of the
distal fruit tissue for Ca by accelerating fruit expansion (Ho, 1998b).
In practice, BER can be prevented by increasing Ca transport toward the
fruit by reducing canopy transpiration (Li et al., 2001) or by canopy Ca
sprays (Geraldson, 1957; Wilcox et al., 1973; Wada et al., 1996; Ho,
1998a; Schmitz-Eiberger et al., 2002). Nevertheless, since BER may occur
in plants and fruits with apparently adequate tissue Ca concentrations,
predicting and preventing the occurrence of BER in glasshouse tomatoes
from measurements of their Ca status has not always been effective.
--- This has led to a recent opinion that Ca nutrition is neither a
primary, nor an independent factor in the development of BER (Saure,
2001)."---
(arrows added for emphasis)
Other than that, David has given you the working theory of BER. Paste
(plum) tomatoes seem to be the most susceptible, and most BER will
diminish in severity, or go away altogether with a little time.
--
- Billy
"Fascism should more properly be called corporatism because it is the
merger of state and corporate power." - Benito Mussolini.
http://www.democracynow.org/2010/7/2/maude
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