Features Agronomy Corn
Use corn gluten for weed and disease control

Golfers enjoying a walk on the fairways may not realize that the reason the
weeds are so scarce is due to an application of corn gluten. Of course, they
likely do not care how the weeds are made to disappear, but the product is being
considered in a collaborative project by potato researchers. Prince Edward Island
Agriculture and Agri-Food Canada scientists Dr. Rick Peters, Dr. Jerry Ivany
and Walter Arsenault are considering corn gluten as a means to reduce weeds
and diseases and provide fertility to potato crops. Registered as a natural
product for turf grass, corn gluten has potential to assist in potato production,
particularly in organic applications.

"Corn gluten has a history of success in the turf industry," explains
Peters, a researcher with the Crops and Livestock Research Centre. "It
does have a nitrogen component and is used as a natural fertilizer, but we also
looked at it for weed suppression and disease control." He says the gluten
breaks down into an acidic compound in the soil that can prevent root development
and may hinder disease development. In two years of corn gluten research, Peters
learned that it will increase nitrogen levels in the petiole and can significantly
reduce some species of broadleaf weeds. There was also indication that corn
gluten reduced the incidence of stem canker and black scurf in potatoes. In
comparison, wheat gluten was less effective when used in similar treatments.

In Peters' trials, he applied the corn gluten in-furrow on top of the seed
pieces for disease control and then applied it over the hill as well for weed
suppression. Both applications were at a rate of 100 grams per square metre
(g/m2) The research measured agronomic factors, such as
yield and pH, against control plots of potatoes using other weed and disease
control methods. Slight reductions in pH levels were noted, according to Peters,
from 5.8 to 5.5, which could be beneficial in terms of scab control. The fertility
results were also positive with nitrogen levels helping to improve the crop.
The research showed that corn gluten worked equally as well as conventional
fertilizers in terms of contributing to chlorophyl production and plant growth.
In terms of disease control, corn gluten did reduce stem canker and black scurf.
There was suppression of corn spurry, cudweed, lamb's quarters and field pansy
in the organic applications, but there was not as strong an effect on weeds
in the conventional production site.

"Corn gluten can't match herbicides in terms of weed control," Peters
admits, "but it does have some value in organic production." While
corn gluten had value in almost all the applications, in comparison to conventional
production methods, its weakness is in its weed control abilities, he concludes.

A weed researcher who worked with corn gluten concurs with Peters' assessment.
Ivany says his results were not positive enough to claim control, although corn
gluten did have some effect on weeds. "According to PMRA, a product needs
to demonstrate an 80 percent reduction in weeds to be considered as providing
control and 60 percent to be designated as giving suppression," he explains.
"We only saw 30 to 40 percent reduction in weed species, which would not
fall under the PMRA guidelines. I really don't see corn gluten as a potential
for weed management in conventional potatoes by itself, but maybe when combined
with other control measures it could help out."

Ivany agrees there is some value in the nitrogen component of corn gluten,
but he believes it would be more valuable if it could be useful for weed control
as well as in organic operations. However, Ivany points out that the corn gluten
would have to be GMO-free in order to fit into the organic philosophy.

In the end, corn gluten has some value in many areas and shows promise for
organic production, in particular. However, more study may be required before
it will be accepted by PMRA or by growers as a viable alternative for weed control,
supplemental nitrogen and disease suppression. In terms of crop nutrition, corn
gluten only provides the nitrogen component of a fertility program; phosphorus
and potash, as well as micronutrients would still need to be added into the
mix. "Certainly, corn gluten looks attractive as a fertilizer, but it would
still need to be supplemented with the other nutrients," Arsenault explains.
Further study may be required to determine just how corn gluten could fit into
a fertility program, he suggests.

While corn gluten has many promising properties and seems to have potential
for numerous applications, both Ivany and Peters do not believe it would be
useful in a conventional potato production system. They do believe, however,
that it holds promise for organic production systems if the GMO issue can be
sorted out. As a readily available and relatively inexpensive product, corn
gluten could fit into either system if growers want to try it, particularly
for its nitrogen component and ability to reduce disease pressure. While the
turf industry has embraced it for its weed control abilities, potato producers
may find it is not effective enough for their needs.

Finally, Peters believes corn gluten deserves further research to fine-tune
its abilities and further analyze its potential. Potato growers looking for
natural, sustainable options for disease and weed control and ways to boost
fertility may appreciate having a natural product to consider. -30-