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#1
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beware pyrethrum sprays
In early spring my Mum enjoyed the butterflies frolicing among the spires
of colourful blooms on her snapdragons. Then she realised it was not the nectar they were coming for--the blossoms were being shredded by hundreds of caterpillers! Not the leaves, just the delicate blooms. So I sprayed the flower heads with a ready-to-go pyrethrum spray. Two days later the blooms had turned brown, burnt by the spray! So she cut off all the flower heads and hoped that more would develop. But ten days later the spires of leaves showed severe burn and the plants had to be cut back to near ground level. Maybe there is still a chance they will reshoot this season. I didn't see any warning on the pack label that plants could be burnt by it. I did apply it generously hoping for a quick kill, but didn't read any caution about being heavy handed. So be warned. I've suggested Dipel or Success for future combat. -- John Savage (my news address is not valid for email) |
#2
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beware pyrethrum sprays
Do you use the spray during the day?
I used a similar spray and it ended up burning my roses - but it was on account of the sun's heat. If I had done it in the evening or very early morning it doesn't happen. BD "John Savage" wrote in message om... In early spring my Mum enjoyed the butterflies frolicing among the spires of colourful blooms on her snapdragons. Then she realised it was not the nectar they were coming for--the blossoms were being shredded by hundreds of caterpillers! Not the leaves, just the delicate blooms. So I sprayed the flower heads with a ready-to-go pyrethrum spray. Two days later the blooms had turned brown, burnt by the spray! So she cut off all the flower heads and hoped that more would develop. But ten days later the spires of leaves showed severe burn and the plants had to be cut back to near ground level. Maybe there is still a chance they will reshoot this season. I didn't see any warning on the pack label that plants could be burnt by it. I did apply it generously hoping for a quick kill, but didn't read any caution about being heavy handed. So be warned. I've suggested Dipel or Success for future combat. -- John Savage (my news address is not valid for email) |
#3
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beware pyrethrum sprays
Maybe you burnt them due to the gas being a sort of refrigerant. In
other words youre spraying a bit too close to the plants. Do it when there is no winf ie early in the morning when theres very little wind. Then you can spray them with some distance in between. Blackadder wrote: Do you use the spray during the day? I used a similar spray and it ended up burning my roses - but it was on account of the sun's heat. If I had done it in the evening or very early morning it doesn't happen. BD "John Savage" wrote in message om... In early spring my Mum enjoyed the butterflies frolicing among the spires of colourful blooms on her snapdragons. Then she realised it was not the nectar they were coming for--the blossoms were being shredded by hundreds of caterpillers! Not the leaves, just the delicate blooms. So I sprayed the flower heads with a ready-to-go pyrethrum spray. Two days later the blooms had turned brown, burnt by the spray! So she cut off all the flower heads and hoped that more would develop. But ten days later the spires of leaves showed severe burn and the plants had to be cut back to near ground level. Maybe there is still a chance they will reshoot this season. I didn't see any warning on the pack label that plants could be burnt by it. I did apply it generously hoping for a quick kill, but didn't read any caution about being heavy handed. So be warned. I've suggested Dipel or Success for future combat. -- John Savage (my news address is not valid for email) |
#4
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beware pyrethrum sprays
g'day john,
might be the difference between natural pyrethrum and the man made version?? the natural stuff very expensive but ultimatlely the safest, organic farmers can only use the natural product last i heard. On Sat, 24 Nov 2007 04:59:57 +0000 (UTC), John Savage wrote: snipped With peace and brightest of blessings, len & bev -- "Be Content With What You Have And May You Find Serenity and Tranquillity In A World That You May Not Understand." http://www.lensgarden.com.au/ |
#5
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beware pyrethrum sprays
anotehr to consider jonno,
when i used to spray i always did so after the heat of the sun, in the afternoons or early evenings. and aerosol cans carry the added down side that the propelants could cause plant damage. On Thu, 06 Dec 2007 22:30:16 +1100, Jonno snipped With peace and brightest of blessings, len & bev -- "Be Content With What You Have And May You Find Serenity and Tranquillity In A World That You May Not Understand." http://www.lensgarden.com.au/ |
#6
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beware pyrethrum sprays
Thats what I meant to say Len, The propellant is a gas, (butane I
believe) and that when its released acts as a refrigerant, It cools things donw rapidly. Same as filling a gas bottle, you see frost form on the surface. IE can cause cold burns on plants. The same as heat burns. Whether there is a difference in early morning or late spraying, I dont know... len garden wrote: anotehr to consider jonno, when i used to spray i always did so after the heat of the sun, in the afternoons or early evenings. and aerosol cans carry the added down side that the propelants could cause plant damage. On Thu, 06 Dec 2007 22:30:16 +1100, Jonno snipped With peace and brightest of blessings, len & bev -- "Be Content With What You Have And May You Find Serenity and Tranquillity In A World That You May Not Understand." http://www.lensgarden.com.au/ |
#7
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beware pyrethrum sprays
"Jonno" wrote in message
u... Maybe you burnt them due to the gas being a sort of refrigerant. In other words youre spraying a bit too close to the plants. Do it when there is no winf ie early in the morning when theres very little wind. Then you can spray them with some distance in between. Oh no. I use the hand pump manual add ons. I don't use a spray can. Its just the heat of the sun. Even if you just spray cold water on the plants- the sun magnifies the droplets and burns the plant. |
#8
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beware pyrethrum sprays
The water on the leaves story has been around for some time, and been
investigated. The problem is really caused by fungal infections due to water on the leaves. The sun does not magnify due to different focal lenght. But plants can suffer from straight out sunburn....Tomatoes for instance get sunscald. I'll try and find the story again if I can... I wonder is some plants are susceptible to the pyrethrum? Blackadder IIVX wrote: "Jonno" wrote in message u... Maybe you burnt them due to the gas being a sort of refrigerant. In other words youre spraying a bit too close to the plants. Do it when there is no winf ie early in the morning when theres very little wind. Then you can spray them with some distance in between. Oh no. I use the hand pump manual add ons. I don't use a spray can. Its just the heat of the sun. Even if you just spray cold water on the plants- the sun magnifies the droplets and burns the plant. |
#9
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beware pyrethrum sprays
Here's a link and part of a theory, which backs up what I read.
http://cahe.nmsu.edu/ces/yard/1999/062899.html But wait I think there's more... Jonno wrote: The water on the leaves story has been around for some time, and been investigated. The problem is really caused by fungal infections due to water on the leaves. The sun does not magnify due to different focal lenght. But plants can suffer from straight out sunburn....Tomatoes for instance get sunscald. I'll try and find the story again if I can... I wonder is some plants are susceptible to the pyrethrum? Blackadder IIVX wrote: "Jonno" wrote in message u... Maybe you burnt them due to the gas being a sort of refrigerant. In other words youre spraying a bit too close to the plants. Do it when there is no winf ie early in the morning when theres very little wind. Then you can spray them with some distance in between. Oh no. I use the hand pump manual add ons. I don't use a spray can. Its just the heat of the sun. Even if you just spray cold water on the plants- the sun magnifies the droplets and burns the plant. |
#10
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beware pyrethrum sprays
On Dec 6, 11:32 am, "Blackadder" wrote:
Do you use the spray during the day? I used a similar spray and it ended up burning my roses - but it was on account of the sun's heat. If I had done it in the evening or very early morning it doesn't happen. BD Pyrethrins are also quite oily which probably intensifies the problem of spraying in hot weather. |
#11
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Some myths regarding gardens or Old Wives tales debunked. myth busters'R us
EXAMPLES OF GARDEN “MYTH”-INFORMATION
Myth #1 Companion planting improves plant growth. Originally based on folklore and tradition companion planting has lots of supporters. Some research done in the 1930’s used chromatography from plant mixtures and evaluated the color patterns they made to determine if they were a good match. (“grow roses with garlic, carrots love tomatoes”, etc.)This has nothing to do with how a plant actually grows or behaves in a garden. Science-based companion planting research has shown that a mixture of varieties of plants is better than mass planting of one type. It makes it hardier to pest attack, as many pests are plant-specific. Match plants with similar water and nutrient needs. Interplanting of tall and short crops so that sun-loving plants can shelter shade plants makes sense. Myth#2 Marigolds repel pests. Data from reputable research shows no such affect. However they do attract beneficial insects with may feed on pests. Myth #3 Ants on peonies are necessary to allow the buds to open. Nope, they are just feeding on the sticky sap produced by the buds. They do no harm to the flowers but they may attack natural enemies that come to feed on the nectar and pollen. Myth#4 Watering on a sunny day will burn plants. The premise here is that water droplets magnify the sun’s rays and burn the leaves. Hmmm, let’s see! Do plants burn when the sun comes out after rain? (There wouldn’t be much left in the tropics then…) Desert farmers routinely use overhead sprinklers to cool and protect young plants from drying out. This myth may have come from the observation of applications of water high in dissolved salts. As the water dries, the salts left behind can burn the leaves. Myth#5 Vitamin B1 reduces transplant shock. This was based on experiments in the 1930’s on detached roots that indicated a positive affect. Multiple experiments since then on a variety of plant species in the lab and field, all show no significant effect of B1 treatment. Researchers from UC Farm Advisory have shown that B1 supplements, which also containing fertilizer, are no better than similar fertilizer products, but cost about ten times as much! Myth#6 Gypsum will “loosen” clay soil, and raise pH. This is true only if you have soil where sodium, instead of calcium or magnesium, saturates the clay. In these “sodic” soils gypsum causes soil particles to gather together, improving structure and water infiltration. Our foothill clay is typically not “sodic”. Gypsum will not “loosen” our soil; organic material such as compost is your best bet. Gypsum’s makeup is calcium sulfate (CaSO4*H2O) and has no effect on pH, but is a good source of calcium or sulfur. Myth#7 Pruning seal helps wounds “heal”. This was based on the premise that a covering of pruning paint or tar protects the cut surface from decay. In reality: wood-rotting organisms may already be in the surface, so you are just trapping them in. The coating can crack leaving the wound even more susceptible to decay. This coating may also actually inhibit the callus formation on the wound, slowing the natural protective process. The bottom line - prune at the proper time for the type of plant, make appropriate pruning cuts, and let the tree protect itself. Myth #8 Buy the biggest plants you can afford to get a jump on growth. Research has shown that a #1 can oak tree will catch up to (and often surpass) a #5 can tree within 1 to 2 years. Ohio state research showed that tomato seedlings that are already fruiting when transplanted yield poorly, even if the fruits are removed. Myth #9 If a plant is pot bound, remedy it by cutting the root ball or teasing roots out and directing downward. New research from the Univ. of Minnesota shows no difference between these treatments and no treatment after 2 years. Here are some final considerations as you evaluate the vast resources of knowledge: * Consider the source. * Does other data support their conclusion? * If there are only testimonial and no data, or appears to be more hype than hypothesis, buyer beware! * And lastly, make sure the data is relevant to your climate, soil, and ecological conditions. Someone in Connecticut may be able to get by without watering all summer by using thick mulch, but here in California, with our dry Mediterranean summers, that probably won’t apply! Andrew wrote: On Dec 6, 11:32 am, "Blackadder" wrote: Do you use the spray during the day? I used a similar spray and it ended up burning my roses - but it was on account of the sun's heat. If I had done it in the evening or very early morning it doesn't happen. BD Pyrethrins are also quite oily which probably intensifies the problem of spraying in hot weather. |
#12
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beware pyrethrum sprays
Fungal spores usually show up in a garden via the wind or insects. One
of the most common are those which cause leaf spot diseases such as early blight. Tomatoes are highly prone to this type of fungal spore and can get infected without you even knowing it. Dark brown patches on the leaves of your tomato plants means they have early blight, which spreads fast on damp leaves. this is probably mistaken for burnt leaves... At the first sign of early blight, it is advised to clip off infected leaves, but only if the foliage is dry. Messing around with damp, infected foliage will only serve to spread millions of fungal spores throughout the garden and infect other tomato plants. After infected foliage is removed (if possible) it is advised to spray down the tomato plants with a mixture of one part milk to four parts water, along with 1 teaspoon of baking soda for every quart of water used. A few drops of liquid soap will help to make the spray stick. The reason this spray is effective is that dried milk when exposed to the Sun's ray's temporarily changes into a disinfectant, while the bicarbonate component of baking soda kills new fungal colonies. Jonno wrote: Here's a link and part of a theory, which backs up what I read. http://cahe.nmsu.edu/ces/yard/1999/062899.html But wait I think there's more... Jonno wrote: The water on the leaves story has been around for some time, and been investigated. The problem is really caused by fungal infections due to water on the leaves. The sun does not magnify due to different focal lenght. But plants can suffer from straight out sunburn....Tomatoes for instance get sunscald. I'll try and find the story again if I can... I wonder is some plants are susceptible to the pyrethrum? Blackadder IIVX wrote: "Jonno" wrote in message u... Maybe you burnt them due to the gas being a sort of refrigerant. In other words youre spraying a bit too close to the plants. Do it when there is no winf ie early in the morning when theres very little wind. Then you can spray them with some distance in between. Oh no. I use the hand pump manual add ons. I don't use a spray can. Its just the heat of the sun. Even if you just spray cold water on the plants- the sun magnifies the droplets and burns the plant. |
#13
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beware pyrethrum sprays
"Blackadder" writes:
Do you use the spray during the day? Probably about mid-morning on a sunny day. I used a similar spray and it ended up burning my roses - but it was on account of the sun's heat. If I had done it in the evening or very early morning it doesn't happen. I'll bear that in mind. But I would expect there to have been on the pack a prominant warning of possible plant damage. I'm surprised that the matter hasn't been brought up on this group before. -- John Savage (my news address is not valid for email) |
#14
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Some myths regarding gardens or Old Wives tales debunked. myth busters 'R us
"Jonno" wrote in message ... EXAMPLES OF GARDEN “MYTH”-INFORMATION ...snip 9 items.... Here are some final considerations as you evaluate the vast resources of knowledge: * Consider the source. Of the 9 items none quotes a specific reference and only 3 quote the institution responsible for the information. * Does other data support their conclusion? None of this analysis quotes supporting evidence and most don't even specify the primary reference. * If there are only testimonial and no data, or appears to be more hype than hypothesis, buyer beware! There's much of this about! * And lastly, make sure the data is relevant to your climate, soil, and ecological conditions. Quite so. Sadly this data, or qualifications relating to it, are also missing from the quoted cases. The case refering to the use of gypsum refers to "our foothill clay" as being significantly different but we have no idea where this is or the nature of such clay. OTOH there are many myths around in the world of gardening and telling people to be wary cannot be bad. Some of the cases mentioned probably do have better information than the myth they are setting out to debunk. Sadly the author only goes part of the way towards doing what they set out to do. David |
#15
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Some myths regarding gardens or Old Wives tales debunked. mythbusters 'R us
Yep Youre partly right. Its an item from America, which does have source.
Unfortunately I only wanted to show that the only way to be sure of things is to check again. I had heard that fungal diseases are spread by water on leaves, and that the "burning" is caused by other things. At times we dont stop to think and accept folk lore as factual, due to it being passed on from father to son etc.. It pays with gardening to find the real facts, and while the internet is a great source of diversity, it does need to be checked against known sources of information. This item I believe came from such a source, but I forget where (Sorry I am also an unknown) We can be pedantic, but I feel that now our attention has been drawn to this, other can check to verify, as there are still others spreading the information that water "burns" leaves. It isnt so! It affects it in other ways. I believe that the spreading of fungal diseases with wet leaves is much more likely, and makes more sense.... David Hare-Scott wrote: "Jonno" wrote in message ... EXAMPLES OF GARDEN “MYTH”-INFORMATION ..snip 9 items.... Here are some final considerations as you evaluate the vast resources of knowledge: * Consider the source. Of the 9 items none quotes a specific reference and only 3 quote the institution responsible for the information. * Does other data support their conclusion? None of this analysis quotes supporting evidence and most don't even specify the primary reference. * If there are only testimonial and no data, or appears to be more hype than hypothesis, buyer beware! There's much of this about! * And lastly, make sure the data is relevant to your climate, soil, and ecological conditions. Quite so. Sadly this data, or qualifications relating to it, are also missing from the quoted cases. The case refering to the use of gypsum refers to "our foothill clay" as being significantly different but we have no idea where this is or the nature of such clay. OTOH there are many myths around in the world of gardening and telling people to be wary cannot be bad. Some of the cases mentioned probably do have better information than the myth they are setting out to debunk. Sadly the author only goes part of the way towards doing what they set out to do. David |
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