Author Topic: Holes in Citrusleaves with yellow brown ring ?  (Read 429 times)

tedburn

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Holes in Citrusleaves with yellow brown ring ?
« on: December 09, 2020, 10:40:02 AM »
Hello Citrusexperts,
discovered on a new plant holes in the leaves with yellow and brown surrounding. Separated it now out of the greenhouse, but would like to know what it is or if it is something that could spread to my other plants ?
Everyone who had this or who knows what this is ?
Thanks for your advice.
Best regards Frank






Millet

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Re: Holes in Citrusleaves with yellow brown ring ?
« Reply #1 on: December 09, 2020, 11:20:10 AM »
Look up alternaria leaf spot on citrus.  There is a lot of control information

tedburn

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Re: Holes in Citrusleaves with yellow brown ring ?
« Reply #2 on: December 09, 2020, 11:38:15 AM »
Thanks Millet for the quick reply, think thats a good diagnose, now I have to look what I have to to,
can I still save the plant which is infected and is there a problem that the fungal is already spread in my greenhouse ?
best regards Frank

lebmung

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Re: Holes in Citrusleaves with yellow brown ring ?
« Reply #3 on: December 09, 2020, 12:09:23 PM »
Bad aeration, increased humidity inside a greenhouse can help spread the disease fast.
Chemical pesticide control is efficient, but I would do it inside a GH in winter.
Take the plants out if they are poted and use a Bordeaux mixture at 0.5%. It's safe for you.

tedburn

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Re: Holes in Citrusleaves with yellow brown ring ?
« Reply #4 on: December 09, 2020, 12:23:52 PM »
Hello Lebmung,
thanks for your advice.  What is a Bordeaux mixture ?
Could you please explain that further, I don' t know this.
Best regards Frank

Millet

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Re: Holes in Citrusleaves with yellow brown ring ?
« Reply #5 on: December 09, 2020, 12:30:39 PM »
The Internet has a lot of control information.  Look up control of Alternaria leaf spot on citrus leaves..

Ilya11

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Re: Holes in Citrusleaves with yellow brown ring ?
« Reply #6 on: December 10, 2020, 03:21:51 AM »
Hello Lebmung,
What is a Bordeaux mixture ?
Bordeauxbrühe
Best regards,
                       Ilya

tedburn

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Re: Holes in Citrusleaves with yellow brown ring ?
« Reply #7 on: December 10, 2020, 06:57:02 AM »
Hello Ilya,
thanks for translation 😅🙏,
does that mean the bordeaux wine or is there an other
liquid which is known or called as Bordeauxbrühe ?
I have isolated now the plants of my greenhouse will cut the leaves of the small plant with the bad leaves and treat them then with the Bordeauxbrühe. The plant has been about 4 weeks in my cold greenhouse, the plan is in spring if its a warmer day to take all the other plants out of the greenhouse and to spray them with Bordeauxbrühe or a fungizid and then the greenhouse.
Or do you think this is in total an oversized measure ?

lebmung

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Re: Holes in Citrusleaves with yellow brown ring ?
« Reply #8 on: December 10, 2020, 07:56:10 AM »
Bordeaux mixture is copper based. https://www.mcgill.ca/oss/article/you-asked/what-bordeaux-mixture
Cutting the leaves in cold weather will cut the sugar supply, and it depends at what temperature you keep the plants. I would wait until spring.
Avoiding high humidity will stop the spread. move the plants into a basement or cold dry room for few days to dry out.
Bordeaux mixture is a contact fungicide and bactericide used in organic culture. It's not curative but it will stop the spread.
« Last Edit: December 10, 2020, 07:59:27 AM by lebmung »

tedburn

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Re: Holes in Citrusleaves with yellow brown ring ?
« Reply #9 on: December 10, 2020, 08:05:31 AM »
Hello Lebmung, thanks a lot for the good explanation, so I will look for that 👏👍