[NAFEX] Fwd: Rooting for Helpful Fungi
lreich at hvc.rr.com
Fri Jan 20 07:42:18 EST 2006
What Dr. Linderman says is true, but you also have to take into
account other factors influencing microbial growth and plant response
to pathogens. In the case of Pythium, for example, this pathogen
thrives best in waterlogged soils which, anyway, are not best for
plant growth. So although using field soil to build up mycorrhizal
inoculum could also multiply a pathogen, problems are minimized by
optimizing other cultural factors such as soil drainage, light, and
air circulation. Then again, just optimizing conditions in the field
is usually all that's needed to promote adequate mycorrhization of
plants -- no need to inoculate with an unknown fungus made from field
soil or a known fungus multiplied in a laboratory.
Lee Reich, PhD
Books by Lee Reich:
Uncommon Fruits for Every Garden
A Northeast Gardener's Year
The Pruning Book
On Jan 19, 2006, at 7:28 PM, Lon J. Rombough wrote:
> Here is a valuable reply from Dr. Robert Linderman on the ARS
> article on growing your own mycorrhizal innoculant from field soil.
> Begin forwarded message:
> From: "Bob Linderman"
> Subject: RE: Rooting for Helpful Fungi
> Re: the article in Ag Research magazine. I have tried to caution
> folks about the “grow your own inoculum” story that has emerged
> from David Douds and colleagues in that they advocate taking raw
> soil and starting pot cultures to produce inoculum on the farm.
> The risk is that you can also multiply pathogens like Pythium while
> growing the AM fungal inoculum. I have done that very thing trying
> to build up some inoculum from field soils. Pythium is happy to
> ride along and grow up with the plant roots of the pot cultures.
> If the Pythiums have the advantage of being faster than mycorrhizal
> fungi, they will win. So, if anyone asks you what you think,
> remember that caution.
> Best regards,
> Subject: Fwd: Rooting for Helpful Fungi
> From: ARS News Service <NewsService at ars.usda.gov>
> Date: January 19, 2006 6:32:47 AM PST
> To: ARS News subscriber <lonrom at hevanet.com>
> Subject: Rooting for Helpful Fungi
> Reply-To: ARS News Service <NewsService at ars.usda.gov>
> STORY LEAD:
> Learning More About Beneficial Soil Fungi
> ARS News Service
> Agricultural Research Service, USDA
> Jim Core, (301) 504-1619, jcore at ars.usda.gov
> January 19, 2006
> --View this report online, plus any included photos or other
> images, at www.ars.usda.gov/is/pr
> Beneficial soil fungi that help plants grow could become easier
> for farmers to use, based on research by Agricultural Research
> Service (ARS) scientists who are studying these valuable organisms.
> The fungi, called mycorrhizal fungi, live inside and outside root
> cells and help them reach for nutrients by extending long threads
> called hyphae into the soil. The plant, in exchange, provides the
> fungi glucose and possibly other organic materials that they need
> to survive. Unfortunately, modern agricultural practices have
> reduced populations of arbuscular mycorrhizal (AM) fungi, the most
> common type.
> By learning more about AM fungi physiology and finding ways to
> grow colonies without host plants, ARS scientists at the Eastern
> Regional Research Center in Wyndmoor, Pa., hope to make the fungi a
> practical option for producers.
> Currently, researchers cannot cultivate an AM fungus without a
> host because the fungus can't complete its life cycle without the
> organic nutrients or other stimuli it receives from roots. Gerald
> Nagahashi, a chemist/cell biologist at ERRC, has been focusing on
> the events that must occur before the fungus can colonize a host
> He developed a bioassay showing that host root components--
> including chemical compounds exuding from the roots, root caps and
> root border cells--induce fungal hyphal branching. The increase in
> branching creates a greater potential for the fungus to find and
> attach to the host root surface.
> Nagahashi and David D. Douds, an ERRC microbiologist, investigated
> how environmental factors, such as chemical compounds from host
> roots, blue light from the sun’s spectrum, and carbon dioxide,
> affect AM fungal growth, either individually or together.
> Their techniques involved growing host roots in sterile culture
> and using sterile fungal spores to study various environmental
> factors individually or in combination. They found that these three
> factors--root chemicals, blue light and carbon dioxide--can all
> work independently to promote growth in AM fungi but are even more
> effective when applied together.
> Read more about this research in the January 2006 issue of
> Agricultural Research magazine, available online at:
> ARS is the U.S. Department of Agriculture's chief scientific
> research agency.
> * This is one of the news reports that ARS Information distributes
> to subscribers on weekdays.
> * Start, stop or change an e-mail subscription at www.ars.usda.gov/
> * NewsService at ars.usda.gov | www.ars.usda.gov/news
> * Phone (301) 504-1638 | fax (301) 504-1486
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