AusBonsai

Is this caused by too much fertiliser?




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Not sure on fertilisers alone...could be a combination of soil too wet + fertiliser? Thoughts anyone else?

No this is caused by thrips in the newly expanding buds. Spray with a good insecticide.

treeman wrote:No this is caused by thrips in the newly expanding buds. Spray with a good insecticide.

Sincere question for you treeman, as your horticultural knowledge is way superior to mine.
I have noticed my tridents can suffer from exactly the same looking tip damage/blackening after a few days of wet weather during the warm months.
I often wondered weather it was thrips, or a fungal outbreak caused by the wet/humid and warm conditions over a few days, as all tips are fine while the weather is dry, sunny and warm.
Can a wet spell cause outbreaks of thrips?

I am not sure if this is related but the info might help others.
Last year, a lot of tridents in the ground suffer from similar problems. Deformed young leaf and blackening tips.
I think others had similar problems as I recall several post discussing the issue.

This year, while dormant, I gave everything a spray with Lime Sulfur. Again, I remember someone posted they do this as a preventative measure.
I think it works as I have not had any problems with any tree this year.

Anyone can recommend any specific insecticide for thrips that I should be using?


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And I forgot to say thank you all!


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Pureheart, I think warmth and humidity get the thrips going but I'm not sure. You can spray with Malathion, Maverick, Confidor, those kind of things.

Got Confidor looks better now! Thanks!


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Problem Is still there and maybe worse now?
What do do? What disease is this one?


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looks like powdery mildew

I think those last pictures are a different problem from the earlier one. New leaves don't appear to have black margins or distorted. The yellowing leaf in one picture has been damaged, possibly too much sun? Just cut that one off. The mottled leaves could be showing sun/dry damage or maybe a nutrient deficiency but from the first post I guess you are feeding regularly. A balanced fert with trace minerals should provide plenty of all nutrients so in that case back to heat damage.
Heat damage is very common in Japanese maples. It is just one of the reasons I try to steer beginners away from this species. I don't think the problem is too bad. Many of mine have similar or worse damage. Soon all the leaves will fall anyway and you'll get a new crop for spring.

Hey all.
I have experienced the same issue on my JM's over the past 2 years. at first i thought my trees were getting sun damage so i moved them to a shadier spot where the leaf growth improved but the problem of curled and damaged new growth was still around. The first flush of spring growth looked great and it is that initial healthy growth that is still keeping my trees alive through summer. I fertilize infrequently but the health of the leaves is good. Clipping off the damaged tips seems to help reduce the problem so I am beginning to think it may very well be thrips, although I have not yet seen any actual sign of the bug???

Thanks all for the help! Shibui I'm a beginner but I love maples too much to miss out!!!


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What to do? Panicking... should I do something?!? I know soon I'll loose the leaves anyways but ... is this slowing the plant growth / health?



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