[tomato] light, not heat

margaret lauterbach (Tomato@GlobalGarden.com)
Thu, 04 Mar 1999 07:56:58 -0700

The July/August issue of "The American Gardener," a publication of the
American Horticulture Society, had an interesting article on "Soil's Hidden
Heroes."  It begins, "Commercial production of mycorrhizal fungi for use in
gardening is in its infancy, but research into these microscopic plants has
been going on for more than 50 years....These specialized fungi...extend
threadlike feeding structures called hyphae into the soil. These absorb
nutrients, which are then shared with host plants. In return the fungi
receive sugars synthesized by the plants.  There is evidence that
mycorrhizae help plants survive stresses such as drought, elevated soil
temperature, and increased salinity and even protect them from certain soil

"Anecdotal evidence for the benefits of mycorrhizal inoculants in gardens
also proliferates, but there are few field studies to back up claims of
their efficacy.  The main reason for this is it is almost impossible to run
controlled field tests using mycorrhizae -- there are just too many

"The bottom line, say mycorrhizal researchers, is that if you already have
healthy soil that contains a lot of beneficial microorganisms, you probably
won't derive much benefit from mycorrhizal inoculants.  If you have just
moved to a new development where the topsoil was replaced with fill dirt
and construction debris, mycorrhizae may be beneficial if used in a program
of organic soil amendments and if use of pesticides and quick-release
synthetic fertilizers is kept to a minimum....

"(Michael) Miller of Argonne National Laboratory says, 'Under most
gardening conditions, you have mycorrhizal fungi already present in the
soil.  You have to have the appropriate fungi to get the optimum response
from different host plants.  Unfortunately, with most commercial
inoculants, you don't know if it's going to work...."