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#1
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Zucchini blossom end rot
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 |
#2
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Zucchini blossom end rot
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 |
#3
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Zucchini blossom end rot
Jonthe Fly wrote:
hope this helps.... http://www.nt.gov.au/d/Content/File/...t_Pest/479.pdf 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 |
#4
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Zucchini blossom end rot
On 4/12/2009 2:17 PM, David Hare-Scott wrote:
Jonthe Fly wrote: hope this helps.... http://www.nt.gov.au/d/Content/File/...t_Pest/479.pdf 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 OK a longer check off list needs to be made it seems. No heavy winds or sudden rain after a period of drought? |
#5
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Zucchini blossom end rot
Jonthe Fly wrote:
On 4/12/2009 2:17 PM, David Hare-Scott wrote: Jonthe Fly wrote: hope this helps.... http://www.nt.gov.au/d/Content/File/...t_Pest/479.pdf 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 OK a longer check off list needs to be made it seems. No heavy winds or sudden rain after a period of drought? No, puzzling isn't it. D |
#6
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Zucchini blossom end rot
On 4/12/2009 10:25 PM, David Hare-Scott wrote:
Jonthe Fly wrote: On 4/12/2009 2:17 PM, David Hare-Scott wrote: Jonthe Fly wrote: hope this helps.... http://www.nt.gov.au/d/Content/File/...t_Pest/479.pdf 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 OK a longer check off list needs to be made it seems. No heavy winds or sudden rain after a period of drought? No, puzzling isn't it. D As you said you had record temperatures, could it be that these have 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.... |
#7
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Zucchini blossom end rot
Jonthe Fly wrote:
On 4/12/2009 10:25 PM, David Hare-Scott wrote: Jonthe Fly wrote: On 4/12/2009 2:17 PM, David Hare-Scott wrote: Jonthe Fly wrote: hope this helps.... http://www.nt.gov.au/d/Content/File/...t_Pest/479.pdf 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 OK a longer check off list needs to be made it seems. No heavy winds or sudden rain after a period of drought? No, puzzling isn't it. D As you said you had record temperatures, could it be that these have 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.... 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 |
#8
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Zucchini blossom end rot
Jonthe Fly writes:
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.... Bees seem to be getting a poor rap here, and all of it undeserved. Allow me to put in a word in their defence. On hot summer days, flowering native trees hum loudly with the sound of beating bees wings. The bees are working even harder in the hot weather! If the number of bees you see in your garden falls off during heatwave conditions, it's because those bees are needed back at the hive to fan the brood (undeveloped bee lavae) in the comb and regulate the temperature of the hive. Bees don't slack off in heatwave conditions, they actually work harder than ever! On the topic of zucchinis, as I have written here many times: the beauty of growing zucchinis is that you DON'T NEED BEES because zucchinis don't need pollination. Provided you harvest the fruit within a day or two of its flower having opened, it doesn't matter whether it has been visited by a bee or not. Only if you want to grow a fruit to maturity do you need bees. But allowing a zucchini to grow large means it loses its flavour, that's why they need to be harvested while young and tender. In addition, not allowing any of the fruit to grow for more than a few days keeps the plant flowering vigorously and producing even more fruit, thus improving the yield. -- John Savage (my news address is not valid for email) |
#9
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Zucchini blossom end rot
On 4/12/2009 10:25 PM, David Hare-Scott wrote:
Jonthe Fly wrote: On 4/12/2009 2:17 PM, David Hare-Scott wrote: Jonthe Fly wrote: hope this helps.... http://www.nt.gov.au/d/Content/File/...t_Pest/479.pdf 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 OK a longer check off list needs to be made it seems. No heavy winds or sudden rain after a period of drought? No, puzzling isn't it. D I also found this, in the Net, which tends to give me the clue I was looking for.. I suspect I'm right. Q: I had a gardener ask me why the blossoms would suddenly fall off his tomato plants. Can you explain that one? Also, why would cucumbers suddenly quit blooming? (Mandan, N.D.) A: One answer to both questions, high temperatures and a lack of adequate moisture. While both like warm temperatures, the hot weather we've been having and the lack of consistent rainfall will cause both blossom abortion and non blooming. Even our zucchini plants are way down on production this year and that's saying something! |
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