Author Topic: Grapefruit Tree branches dying - need diagnostic help!  (Read 2544 times)

MangoFang

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Grapefruit Tree branches dying - need diagnostic help!
« on: September 18, 2014, 03:12:22 PM »
I had posted this over on the Tropical Fruit Forum and was told it should be over here....so....
I've attached a couple pictures of the tree and what appears to be something
on some of the branches....is this gummosis or something like that?  Is it
treatable?  Sorry, some of the pics are a bit blurry....


Thanks, Gary







Blake Branch

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Re: Grapefruit Tree branches dying - need diagnostic help!
« Reply #1 on: September 18, 2014, 10:14:08 PM »
It looks like gummosis caused by phytophora. You can treat it with copper based fungicides.

http://www.ipm.ucdavis.edu/PMG/r107100411.html

MangoFang

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Re: Grapefruit Tree branches dying - need diagnostic help!
« Reply #2 on: September 19, 2014, 02:11:17 PM »
Thanks a lot, Blake.  I'll go find something with copper in it!

Gary

Blake Branch

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Re: Grapefruit Tree branches dying - need diagnostic help!
« Reply #3 on: September 19, 2014, 09:55:11 PM »
Before I wrap my trees trunks during the winter, I coat them with a mix of Kocide 3000 and latex paint (1/2 lb of product per quart of paint).  I haven't lost a tree yet from any type of phytophora complex.  Kocide 3000 is a copper hydroxide product.  Just be careful if you live in an area with low humidity or if you use phosphite products, as both can cause injury from copper applications.

Millet

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Re: Grapefruit Tree branches dying - need diagnostic help!
« Reply #4 on: September 20, 2014, 08:24:04 PM »
Is this tree watered too frequently, or is the tree growing in a poorly draining soil location?  There are several commonly used chemicals to control the problem.  Ari-Fos (Phosphorous acid), is commonly used by Southern California growers. Bayer produces one called Aliette fungicide. Fosetyl-Al is another good treatment. - Millet

Blake Branch

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Re: Grapefruit Tree branches dying - need diagnostic help!
« Reply #5 on: September 20, 2014, 11:37:13 PM »
If you do use a phosphorous acid product, do not use copper with it.  The phosphorous acid will act as a carrier and make the copper and other metals absorb into the plant at toxic levels.  On a positive note, I've used phosphorous acid as a substitute for Ridomil Gold for phytophora control in other crops.  I apply it through the drip irrigation system, where Ridomil Gold has to be applied to the soil with a sprayer.  The cost per acre is also substantially less, $12 per acre compared to $130 per acre for Ridomil.

MangoFang

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Re: Grapefruit Tree branches dying - need diagnostic help!
« Reply #6 on: September 22, 2014, 12:12:50 AM »
Well, you guys got me a bit confused now.....I live in the desert....the tree gets watered every other day, and my soil is very sandy, so drainage is not a problem....yes low humidity, too, generally.

I just changed the watering situation from sprinklers, that were hitting into the canopy of the tree, to bubblers on the soil level.  I was planning on scraping off the diseased bark and "painting" onto the damaged, but now cleaned part of the trunk, with some copper fungicide, mixed with later paint.  Do you guys think that will work for my situation?


Thanks....MangoFang