Corn Gluten
Meal for Crabgrass Control
John
C. Stier
The idea of using corn gluten meal
for weed control burst on the scene in the early 1990's after
Dr. Nick Christians at Iowa State accidentally discovered its
herbicidal properties while he was testing it for suppression of
turf diseases. After several years of efficacy studies and
product development, corn gluten meal has gained national
attention as being the first effective "organic"
herbicide. Corn gluten meal is not a registered pesticide
because the U.S. EPA has granted an exemption for corn gluten
meal as an herbicide.
Corn gluten meal is a product of
the wet milling process. It is a pre-emergent herbicide which
inhibits root formation during germination. It is currently
labeled for control of crabgrass, barnyardgrass, foxtails (Setaria
spp.), dandelion, lambsquarters, pigweed, purslane and
smartweed. Data suggest it has at least some activity on an even
wider variety of plants. It is safe to use on established turf.
DO NOT use corn gluten meal in an area in which you are trying
to establish turfgrass.
Research shows 50-60% control can
be achieved in the first year when applied at 20 lb per 1000
ft2. Studies suggest that control is improved in successive
years and as use rates increase. Currently it is sold as a dry
product under various trade names, including Dynaweed, Safe 'N
Simple, Earth Friendly, W.O.W.!, Corn Gluten Meal Herbicide, and
Propac. It is sold for the homeowner market in retail stores as
Concern-Weed Prevention Plus. Until recently it was only offered
in powder form. Now a granular form is available which can be
more easily be applied with Vikon spreaders, rotary and drop
spreaders. Application rates vary from 12 to 20 lbs per 1000 ft2
depending on the intended use. For crabgrass control in turf,
two applications are recommended at 12 lb/1000 ft2, once in
early to mid-spring and another in early to mid-August. Since
the corn gluten meal is about 10% nitrogen, this catches two
flushes of crabgrass and spreads out the nitrogen effect. Two
applications at 12 lb/1000 ft2 will provide nearly 2.5 lb N/1000
ft2 per year. The nitrogen is in a slow release form so there is
little to no potential for foliar burn. Bulk orders cost about
$950/ton; 50 lb. bags run between $25 and $30. This is the same
corn gluten meal sold at feed mills for animal feed; however, it
is pelletized for easier and more uniform application.
Portions of at least two proteins
in the corn gluten meal, called peptides, are the active
ingredients in corn gluten meal. Laboratory studies show the
peptides themselves to be significantly more effective at
preventing weed germination than the corn gluten meal itself.
Unfortunately the peptides do not persist in the soil when used
as a spray long enough for effective control. Current research
is aimed at isolating and packaging these peptides to produce a
sprayable product. |
