white fungus (?) on apple tree roots

caflowerluverNovember 14, 2009

Can anyone tell me what this is and how to get rid of it? We have had small patches in the past but never this bad.


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I'm no expert but does any of it look like the picture in my link.

Here is a link that might be useful:

    Bookmark   November 14, 2009 at 11:46PM
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Could you please tell us where you live, what your recent rainfall situation has been, and describe the drainage of your orchard area?

Photo #2 appears to show soil that has been subject to running water at the base of the tree. If drainage is poor around this tree, it is possible that the lower area has been partially drowned, killing the root tissue and permitting the formation of opportunistic fungal growth. I know of no way to cure this, and would say the prognosis for this tree is poor.

It is also possible that thisisme is correct about presence of wooly aphids, but it would take a much closer look to determine this. My personal opinion is that you have fungal growth on necrotic wood.

Don Yellman, Great Falls, VA

    Bookmark   November 15, 2009 at 1:17AM
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I have to agree it looks like this tree is planted in a depression that fills with water either from rain or irrigation and stands in water a good bit of the time. To save the tree would mean re-terracing the area to keep the water away from the tree trunk. If this tree is being watered, the water should be applied at and beyond the drip line. Al

    Bookmark   November 15, 2009 at 10:17AM
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alan haigh

Does look kindof like RAA but I've never seen them so concentrated. Tree is pretty old so I don't know why it would suddenly have an issue with drainage out of the blue. Soil looks sandy and not soppy as well. I've never seen a fungus that looked like that on drowning apples anyway- have you Don?

Anything we should know about changes in the environment- an unsually wet season, installed sprinklers, fertilization program, etc? Where are you located?

Maybe you can take a small piece of the infected bark to your cooperative extension. If you have a funtional one it is a more accurate way to get diagnosis than from pictures on the internet. Sometimes you need a microscope.

    Bookmark   November 15, 2009 at 10:59AM
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Thanks everyone for the replies. I thought it was fungus but DH says it is more like nodules that are growing on the roots. The roots also put out a lot of suckers.

I live on the Central CA Coast near Santa Cruz. We only get rain in the winter from Nov. to April. We have had one rain fall since last May and it dried up right away. No fertilizer, or sprinklers. We do water once a week with a soaker but it goes immediately into the ground. No standing water. We have very sandy soil that drains well. It is over a septic leach field.

The tree has been in the ground for 23 years in the same location. It is a Stayman Winesap apple. It has only started doing this about 7 or so years ago but never this bad. We also get curly leaf and some white powery stuff on the leaves. I thought it was the same thing on the roots but it is totally different. Over the years we have sprayed with malathion, sulfer (dormant mix in winter), and copper oil dormat spray.

Thanks for the help.

    Bookmark   November 15, 2009 at 12:36PM
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alan haigh

Santa Cruz is bound to have a very good cooperative extension- you're just a couple hours from UC Davis. Of course with the financial issues in your state there's no telling what's been cut. There are also numerous commercial orchards a short drive from you from which you could probably get some expert advice for free. If it's not WAA you have me stumped. Local, knowledgeable advice is the most useful.

    Bookmark   November 15, 2009 at 1:39PM
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jean001(z8aPortland, OR)

And when you find out what it is, then please come back to tell us. That way, we all learn.

    Bookmark   November 15, 2009 at 5:48PM
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Take a sample along with your pictures to the UCCE office in Watsonville and mark it to the attention of Steve, the farm advisor. He is one of the most knowledgeable tree experts in the state. It may take a couple of weeks for your answer, but I am sure he will be interested in your problem. Al

    Bookmark   November 16, 2009 at 8:53AM
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Thanks everyone for the replies. I will take a sample to the cooperative extension office and see what they say. And when I find out anything I will post the answer.

    Bookmark   November 16, 2009 at 7:50PM
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If you can post a closer picture ID would be more possible, but I think you may have 'Wooly Aphids', a bad pest and it can seriously weaken the tree, since the root feeders are hard to kill . You will see feeding on the main trunk, "usually in pruning wounds and other damaged areas. The top infestation can be killed with malathion and Oil, but again, the root feeders are tough to deal with. I'd spray the ones you can see, and be careful not to prune the tree too severely next winter. Make sure you have adequate Nitrogen to maintain vigor.

    Bookmark   November 19, 2009 at 11:43AM
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jean001(z8aPortland, OR)

Here's a good "test" to determine if it's woolly apple aphids. Use your finger to squish here & there. If your finger is stained with purple, it's woolly apple aphid.

And it looks like you have a humongous population!

And yes, the small hard galls (nodules) you see/feel, develop from the insects' feeding.

    Bookmark   November 22, 2009 at 3:01PM
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