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How to defeat pecan scab?

Pecan    None Given

Hi there,
I'm from center Italy, and I have two grafted pecan plants, a Kiowa and a Cape Fear.
After a month I noticed some spots and it is probably scab.
I eliminated the affected leaves and treated with tebuconazole.
The scab is probably due to two walnuts near my pecans which are probably affected by scab.
Now, I would like to treat this winter with bordeaux mixture, spray after the fall of leaves, a spray after pruning and a spray just before the opening of buds.
According to you should I spray also tebuconazole on new leaves as prevention?
Should I try to spray also the affected walnuts?


Posted by: Mirko (1 point) Mirko
Posted: November 15, 2016




Answers

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Generally the continuous application or too many applications of the same fungicide may lead to pathogen developing resistance to that particular fungicide. So alternating triazoles (tebuconazole) with organometals helps in reducing the resistance development in fungi .

http://www.apsnet.org/edcenter/introp...

The pathogen normally overwinters in lesions on the leaves, shucks, and twigs of previous year infection, which serves as primary inoculum. And the present year infections act as secondary inoculum. So the disease occurs throughout the year. Removing and proper disposing of infected plant debris helps in reducing the primary inoculum.

According to University of Oklahoma, the growers are recommended to start spraying the susceptible varieties from early spring ie., when the developing leaves are first exposed to inoculum from the overwintered lesions.

I am not sure you can use tebuconazole to control scab on the walnut tree. But according to University of Illinois, Urbana-Champaign to control scab, anthracnose, yellow leaf blotch, and other fungus leaf spots and blights growers can spray benomyl/dodine/maneb/ mancozeb starting when the leaves begin to unfold and continue at 2-week intervals 3 or 4 times.
http://www.aces.uiuc.edu/vista/html_p...


Posted by: Dr. Ravishankar Narayana (8 points) Dr. Ravishankar Narayana
Posted: November 16, 2016




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