Plant pathologist holds a plant with compost added
to it and a technician holds a plant without compost. Click the image for
more information about it.
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Beneficial Fungi Work
May 6, 2004
Certain fertilizers can actually inhibit
beneficial, naturally occurring fungi that help plants use water and nutrients
while suppressing diseases, according to an Agricultural Research Service scientist
studying these beneficial root-dwelling fungi.
ARS plant pathologist Robert Linderman at the
Crops Research Laboratory in Corvallis, Ore., is studying how these fungi,
called mycorrhizae, interact with fertilizers and other soil amendments that
have been commonly used in agriculture over the past half century.
Linderman is one of only a few scientists studying how mycorrhizae affect
the nutrition and health of nursery crops. He has measured the level of
mycorrhizal colonization of roots to see whether various materials added to
soil help or inhibit fungal growth. He studied a range of commercial
fertilizers and found that organic ones are usually compatible with
mycorrhizae, while phosphorus-rich inorganic fertilizers usually inhibit them.
He also looked at peat moss, a popular additive to potting mixes used to
grow nursery crops. He found that in some cases it helps mycorrhizal
associations, while in others it hinders the fungi. Coir, a coconut fiber that
has become a popular potting mix additive, does not inhibit mycorrhizae, but it
may reduce growth of some plants.
Linderman is currently studying various types of composts to see what, if
any, effect they'll have on the establishment of mycorrhizae. His initial
finding is that some composts may suppress the fungi because of high phosphorus
After spending years researching these important fungi, Linderman believes
that he will now be able to advise growers as to which potting mix additives
will help establish mycorrhizae that can enhance plant growth and health.
more about this research in the May 2004 issue of Agricultural
ARS is the U.S. Department of
Agriculture's chief scientific research agency.