THE USE OF A NATURAL PRODUCT FOR THE CONTROL
OF ANNUAL WEEDS IN TURF
NICK CHRISTIANS
IOWA STATE UNIVERSITY
The last few years have brought increased public interest in
environmental issues concerning the use of pesticides. This has
been particularly true in the turf industry where the general
public may be involved in the applications of pesticides to their
own lawns or where they may see the application of these materials
on golf courses or by lawn care companies. With this concern, has
come an increased interest in natural products that are perceived
as being safer than traditional synthetic pesticides.
In 1986, a research project involving food-grade corn meal as a
growth media for a microorganism produced some observations that
led to the patenting of a natural organic product for the
preemergence control of annual weeds. The objective of this work
was to establish a Pythium fungi in the soil of a new golf course
green that had been constructed at the Iowa State University
turfgrass research area. The effects of this pathogen were then
to be observed on creeping bentgrass (Agrostis palustris) that was
to be seeded on the infested soil.
The Pythium was cultured in the laboratory for several weeks on
the corn meal and then taken the field area where it was placed on
the surface and tilled into a 3 to 4 inch depth of the soil
(Figure 1). Along with the inoculated corn meal plots, plots of
the same size were treated with fresh corn meal that had not been
treated with Pythium. The same total amount of corn meal was used
in the two separate treatments. A third 'control' plot to which
no corn meal applied was also established. Three cultivars of
Creeping bentgrass were then seeded in strips over the top of the
plots.
The attempt to establish Pythium in the treated plots was a
failure and normal germination occurred in those areas. Normal
germination also was observed in the control plots. But in the
plots that had received the fresh corn meal, establishment was
greatly reduced.
The reason for th