Author Topic: Fungal disease on new flushes?  (Read 1019 times)

matt_citrus

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Fungal disease on new flushes?
« on: August 24, 2021, 07:23:05 PM »
30 or so trees in very close proximity and the only one experiencing this is a Shiranui. New growth flushes are browning and dying off. Is this one of the common fungal infections?

   

matt_citrus

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Re: Fungal disease on new flushes?
« Reply #1 on: August 24, 2021, 09:27:28 PM »
Perhaps have answered my own question but offer it to the experienced growers for confirmation.

Looks very much like the Alternaria Brown Spot symptoms on young growth in this recent research paper:
Alternaria brown spot on new clones of sweet orange and lemon in Italy



And in this UF publication: Alternaria Brown Spot

orangedays

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Re: Fungal disease on new flushes?
« Reply #2 on: August 25, 2021, 12:00:47 PM »
It looks as if the damage is confined to only the tenderest part of the new leaves; it may be a reaction to an environmental stress, rather than fungal invasion.  Did you spray the citrus recently? Sometimes insecticidal soap burns tender young growth while mature growth shows no damage. Other types of horticultural sprays/fertilizers can also burn young shoots. Certain varieties are more sensitive than others. Bright sunlight on water or oil spray droplets can also cause burning on tender growth. Perhaps to be safe, isolate the plant, but don't give up hope.

Millet

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Re: Fungal disease on new flushes?
« Reply #3 on: August 25, 2021, 02:49:03 PM »
It does not look like Alternaria Brown Spot. 

Citradia

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Re: Fungal disease on new flushes?
« Reply #4 on: August 25, 2021, 09:41:02 PM »
I had brown die back on new growth on my Santa Teresa lemon last year, potted, after almost daily rains all year. I brought it out of the rain, snipped off the infected leaves, and sprayed it with copper fungicide. It has not had a problem since, and is back outside in the rain like all my other in ground and potted citrus. I think it was just more sensitive to too much rain and I wonder if it didnít get a fungus from being too close to some rhododendron that also have been suffering from a brown leaf disease. No problem this year, but not as much rain this year either.

matt_citrus

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Re: Fungal disease on new flushes?
« Reply #5 on: August 27, 2021, 10:14:55 PM »
It does not look like Alternaria Brown Spot.

The mystery continues then.

matt_citrus

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Re: Fungal disease on new flushes?
« Reply #6 on: October 19, 2021, 07:26:01 PM »
Does anyone have suggestions for treatment? New growth continues to be affected.

Flgarden

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Re: Fungal disease on new flushes?
« Reply #7 on: October 19, 2021, 09:54:56 PM »
I have the same issue with a few potted trees, not citrus. I tried sprays, replanting in different soil, fertilizers, macros, part shade, full sun... Nothing works. 

sc4001992

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Re: Fungal disease on new flushes?
« Reply #8 on: October 20, 2021, 01:38:49 AM »
Matt, how cold does your night temperature get now?  Maybe it's just cold damage to young leaves.
I would just cut off the branches with the black leaves that look damaged. Doesn't look like a big deal but you never know.

matt_citrus

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Re: Fungal disease on new flushes?
« Reply #9 on: May 23, 2022, 07:13:58 PM »
Coming back to this, I'm fairly certain now that it's Alternaria Brown Spot.

Don't have a good mechanism for control yet given how often it rains.

Millet

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Re: Fungal disease on new flushes?
« Reply #10 on: May 23, 2022, 09:17:25 PM »
Fungicides ae usually needed for adequate control.  Maneb, mancozeb, chlorothalonil, metiram, strobilurins, and copper fungicides are the most widely used products.  Where the disease is severe and environmental conditions are favorable for he pathogen, several applications are usually required to produce acceptable control.  In humid climates, applications begin when the spring flush is one-fourth expanded  Where humid conditions exist, follow-up sprays could be required.   Good Luck with your tree.  We would appreciate hearing out how your tree is doing.  (Taken from the Compendium of Citrus Diseases.)

 

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