Zucchini blossom end rot

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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. Well my zuccs have not been watered unevenly, they have neither been saturated not allowed to wilt and they are well mulched. 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. As a short term thing I am cutting them early which makes for nice tasty fruit but a small harvest.
Any ideas from experience?
Any references to a detailed explanation of how BER happens, in particular how uneven watering results in a mineral problem?
David
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Could there be a problem with water penetration due to the mulch? I know I have to be quite careful of mulch on our low pressure, gravity fed, country water supply and fluff the mulch every now and then or otherwise the watering isnt' even.
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FarmI wrote:

I don't think so, the zuccs and other stuff in that bed are growing quickly and not wilting on hot days so I reckon the water is good. But I will insert the diagnostic finger more often to be sure. Thanks.
David
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"David Hare-Scott" wrote in message

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.
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.

I'm curious; did a soil analysis/test indicate you needed the lime and gypsum or is this just a gardening "best practice" method?
If you care to share; what type is your soil, pH, amendment regime, fert/schedule, etc.?

Try these:
* http://www.spectrumanalytic.com/support/library/ff/Ca_Basics.htm
** http://www.actahort.org/members/showpdf?booknrarnr 5_23
http://www.springerlink.com/content/ww87lw2086rj3v71 /
http://jxb.oxfordjournals.org/cgi/content/abstract/44/2/509
General reads on BER: http://pubs.caes.uga.edu/caespubs/horticulture/blossom-rot.html
http://wihort.uwex.edu/fruitveggies/TomatoDisorders.htm
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gunner wrote:

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.

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.

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.

thanks for the refs
David
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On 3/12/2009 9:40 AM, David Hare-Scott wrote:

http://www.nt.gov.au/d/Content/File/p/Plant_Pest/479.pdf
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Jonthe Fly wrote:

Thanks. None of the listed ways that insufficient calcium would be available seem to apply. I may just continue cutting most of them small (zucchini flowers are very "in" you know) and leave a few to grow, or not, and await developments.
David
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On 4/12/2009 2:17 PM, David Hare-Scott wrote:

OK a longer check off list needs to be made it seems. No heavy winds or sudden rain after a period of drought?
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Jonthe Fly wrote:

No, puzzling isn't it.
D
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On 4/12/2009 10:25 PM, David Hare-Scott wrote:

affected pollination at that crucial time. I have the idea planted in the back of my mind somewhere, that pollination stops when the temperature gets too high, and it may also be that bees stop pollinating for the same reason....They slack off on hot days....
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Jonthe Fly wrote:

This is true of some species such as tomatoes but I have not heard of it regarding marrows. That doesn't mean that it isn't so.
David
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On 5/12/2009 8:20 AM, David Hare-Scott wrote:

http://www.gardenersnet.com/atoz/pollenfaq.htm
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On 5/12/2009 8:20 AM, David Hare-Scott wrote:

Of course the nose is on your face.
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On 5/12/2009 8:20 AM, David Hare-Scott wrote:

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Jonthe Fly wrote:

I do not rush into conclusions. I have grown zuccs right through summer here for years, which is just as hot or hotter than the last month, and not had the problem of BER. I think the prolonged flagellation of this particular horse has just about reduced it to component molecules.
D
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On 6/12/2009 5:21 PM, David Hare-Scott wrote:

answer. Have they been eliminated? Experience in servicing electronics has taught me that. I would have thought the extreme hot weather would have been the first thing to come to your mind. It does with me. I reckon it could be climate change. Of course not living where youre living, I wouldnt have known about the heat you were experiencing.....But youve gone strangely quiet on this.... Never mind.
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The name is different, but the syntax is familiar. My, aren't you the shy one.
Sooo, you've read Sherlock Holmes, eh? Well, bully for you. And then, your mind just seems to just caved in.
I someone stood near you, which ocean would they hear?
--
When you give food to the poor, they call you a saint. When you ask why the
poor have no food, they call you a communist.
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Wildbilly wrote:

He appears to be posting from an Australian ISP. Who do you think it is?
David
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My bet is on the Ghost of Christmas Past!
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That just means that we should have stepped on the eggs when we had a chance. They're spreading.
--
When you give food to the poor, they call you a saint. When you ask why the
poor have no food, they call you a communist.
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