On 3/12/2009 9:40 AM, David Hare-Scott wrote:
gunner wrote:
"David Hare-Scott" wrote in message

"My zuccs have BER!"

"As I understand it the problem is due to deficiency of
calcium in the plant which can be brought about by uneven water
availability or lack of calcium in the soil.".

Absent more specifics, I believe that is more SWAG than fact.

Consider the chemical distribution of Ca w/in the plant.
Most likely your plant's available calcium is being diverted from the
fruit & going to the leaves where it is needed more at that
particular time, say for transpiration.


I am beginning to suspect that this is the case. We have had a rather
warm spring and these plants are putting on growth at a high rate.

Ca is not a mobile nutrient, i.e. going where it is best needed. If
BER occurs when temps are high, try slowing the plant's transpiration
rate to get a better Ca distribution. Note, even if you have
adequate soil Ca, its uptake can be limited by other factors such as
listed in the Spectrum Analytic article* below . If BER is a
constant problem, try the preventive measure outlined in the ISHS
abstract ** below.

The soil has been amended with lime and gypsum.
They are growing strongly with a multitude of flowers and fruit
setting. One odd thing is that normally this strikes on the fruit
when they are quite small but this time they are getting nearly to
cutting size before it starts.

I'm curious; did a soil analysis/test indicate you needed the lime and
gypsum or is this just a gardening "best practice" method?


I have not had a soil analysis done as I don't see the need. I grow a
very wide range of fruits and veges quite successfully and I see no
signs of consistent problems which would lead me think the soil has
deficiencies. I have done pH tests myself using a dye indicator system
which I believe to be reliable and accurate enough for the purpose.

If you care to share; what type is your soil, pH, amendment regime,
fert/schedule, etc.?


The soil profile is about 20cm of nearly black silt over plastic
smectite clay (which I don't disturb). The silt is somewhat friable but
has quite a bit of clay and without amendment still clumps together to a
degree when wet. The starting pH is 5.5 and I have been bringing it up
over time with lime, it is about 6 to 6.5 now so I don't add lime as a
rule now. When I established the plot 4 years ago I added gypsum to help
break up the clay. I add chicken litter, horse manure, a touch of
soluble potash and compost every year and mulch with hay which gets
incorporated. I add a seaweed extract every two years. The citrus get a
soluble trace element mix when they need it. - about every three years.

The result is after 4 years the vege plot is much more friable and now
has a good infiltration rate, for a clay-based soil it is very good.
Given the clay and organic matter in the soil the TEC (and CEC) would be
quite high but I haven't measured it. I see no signs of nutrient runoff
downhill. There is no limestone or sodised soil around the area and the
river water I use to irrigate has an EC which varies with rainfall but
is typically around 200-300 microsiemens/m. I use raised beds which
gives drainage and about 40cm of depth.

The average annual rainfall is about 1100mm but the fall is extremely
erratic which is a potential problem. We have not had prolonged rain
since the summer veges were planted. However, the clay subsoil acts a
sponge soaking up water during rain and the releasing it in between
times, to illustrate, it is two months since we had significant rain,
and five weeks since anything useful in the rain gauge at all and in the
last month we have had record temperatures for the month up to 41C. Yet
my pasture is green and growing very strongly without irrigation. I have
been monitoring the veges and fruit trees and irrigating them as required.

So to summarise, I see no cause for calcium problems except the zuccs
are growing too fast for their own good.

"Any ideas from experience?"

"Any references to a detailed explanation of how BER happens..."

Try these:

* http://www.spectrumanalytic.com/supp.../Ca_Basics.htm

** http://www.actahort.org/members/show...knrarnr=145_23

http://www.springerlink.com/content/ww87lw2086rj3v71/

http://jxb.oxfordjournals.org/cgi/co...tract/44/2/509

General reads on BER:
http://pubs.caes.uga.edu/caespubs/ho...ossom-rot.html

http://wihort.uwex.edu/fruitveggies/TomatoDisorders.htm

thanks for the refs

David
hope this helps....

http://www.nt.gov.au/d/Content/File/...t_Pest/479.pdf