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  • From: "Dr. Lucky Pittman" <lucky.pittman@murraystate.edu>
  • To: "'North American Fruit Explorers'" <nafex@lists.ibiblio.org>
  • Subject: Re: [NAFEX] Witches Broom
  • Date: Thu, 10 Feb 2011 14:42:17 -0600

I've not seen it on walnuts - but have seen 'bunch disease' on pecans - and
understand that it also afflicts walnuts of various species. Prevailing
thought, so far as I'm aware, is that it is caused by a mycoplasma-like
organism. Causes a "witch's broom"-type of growth.

Lucky

-----Original Message-----
From: nafex-bounces@lists.ibiblio.org
[mailto:nafex-bounces@lists.ibiblio.org] On Behalf Of Kieran &/or Donna
Sent: Thursday, February 10, 2011 12:17 PM
To: North American Fruit Explorers
Subject: Re: [NAFEX] Witches Broom

Witches broom is a word for a deformed growth on a plant. It can be a bud
sport, as in many of the prostrate evergreens for sale for landscaping.
People who deal with evergreens tend to watch for such a growth to make
their name and possibly their fortune. Witches broom growths can indicate
virus, usually that is what I think when I see them. For example, when
potatoes sprout, the virused ones often have weird thin growth. Rose
rosette is an example I see around here on wild multiflora roses, and
sometimes on tame roses. But there are funguses that cause witches broom
type growths, such as rosette in blackberries. I try to pick them out as
soon as I see them so they can't spread. It's not like seeing rust and
knowing the entire plant is infected forever.
The witches broom that Hector referred to also grows on the native
butternut trees in this area. I have seen 2 such trees in 27 years in
Tennessee. One was one of several seedlings from butternut seeds my son
picked up in Vermont. Did they catch the disease from some tree off in our
woods? Did it come on the seed? Donna

Some short quotes:
Diseases caused by Fungi:

Butternut canker, Sirococcus clavigignenti-juglandacearum.
This serious disease is a problem for butternuts and does not affect black
or English walnuts. Symptoms include dead branches, top dieback, discolored
bark which has an inky black fluid coming from cracks in the spring and
sooty patches, usually with a whitish margin, in the summer. Cankers are
elongated and sunken, and frequently lethal.Cutting and removing infected
wood will slow the spread of infection, but there are no known controls.

----------------------------------
Bunch disease also attacks butternut. Currently, the causal agent is thought

to be a mycoplasma-like organism. Symptoms include a yellow witches' broom
resulting from sprouting and growth of auxiliary buds that would normally
remain dormant. Infected branches fail to become dormant in the fall and are

killed by frost; highly susceptible trees may eventually be killed.
Butternut seems to be more susceptible to this disease than black walnut.

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