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Post by sal1991 on May 6, 2014 19:34:06 GMT
Hi,
I am new to growing Dahlias. Today when I went to check on them (they are currently in pots ready to be potted on) I noticed that one of them had white streaks on the leaves and stem. The first thing I thought is it could be is thrip however I could not see any on the plant and after researching the internet cannot find any pictures that are similar.
Does anyone know what this might be?
Thankyou
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Post by daitheplant on May 6, 2014 19:51:07 GMT
Possibly whitefly and/or mealy bug and/or scorch and/or woolly aphid.
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Post by Deleted on May 6, 2014 23:08:31 GMT
Possibly whitefly and/or mealy bug and/or scorch and/or woolly aphid. Its not thrip, they are not active until mid summer when the wheat corn begins to ripen and the females migrate off cerial crops in search of water. At first sight it does look like sun scorch, which is easily done this time of the year. Young dahlias / cuttings wont tollerate direct sun after being watered. Water on their leaves magnifies the sun's rays. If this is the only plant then I would isolate it from the rest or personally I would bin it to be safe !! |
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Post by Tel on May 7, 2014 7:25:42 GMT
I agree the leaves look like scorch marks.
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Post by daitheplant on May 7, 2014 19:36:17 GMT
The leaves DO look scorched, but the stems look as if they have wooly aphids.
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Post by scrumpy on May 11, 2014 18:57:13 GMT
My own theory is that it is due to transpiration, caused by excessive heat, leaving behind the powdery white salt like material.
It's happened to me in the past in the greenhouse, and it has also happened to more established plants in the garden, after using foliar sprays.
A good spray of water to remove the residues is all that I do.
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Post by sal1991 on May 12, 2014 23:02:21 GMT
That sounds identical Scrumpy. I went the day after and most of it had gone and I could wipe/dust the rest off. Thank you all for your help, glad it wasn't anything too serious.
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Post by Deleted on Jul 7, 2014 12:11:43 GMT
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Post by Cherry on Jul 10, 2014 14:51:40 GMT
What an amazing colour match.
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Post by lesley on Jul 11, 2014 17:33:36 GMT
I have a very large dahlia growing in a pot 'Sir Alfie Ramsey' but the leaves are turning a yellow colour is it a deficiency of some thing  |
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Post by scrumpy on Jul 11, 2014 17:40:53 GMT
Is it all the leaves or just the lower ones? If it's just the lower ones, pull them off. I do that as a routine with all my dahlias as they would end up going all colours anyway if I left them on. In pots, they would need extra feeding anyway. Sir Alf in a pot should be quite interesting  |
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Post by lesley on Jul 12, 2014 7:26:44 GMT
Thanks Scrumpy, why will it be interesting I grew it in there last year and it did very well, how often do I fed it ? |
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Post by scrumpy on Jul 12, 2014 7:53:49 GMT
Sir Alf in the garden grows huge, so I couldn't envisage how it would look in a pot. You must show us a piccie when it's in bloom.
As to feeding, I'd treat them like tomatoes. Use a fertiliser containing seaweed as that has the extra trace elements, or something like Chempak high potash.
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