Friendly Fungus With Dirty Name Takes on Southern Menace
ARS News Service
Agricultural Research Service, USDA
May 25, 1999
Jan Suszkiw, (301) 504-1630, firstname.lastname@example.org
Wiping out smut is a campaign for some folks. But in Louisiana's bayou
country, Rex Millhollon is actually trying to encourage it--loose kernel
smut, that is. The fungus, Sphacelotheca holci, is the respected
agronomist's latest jab at halting Johnsongrass, a loathsome southern weed
that keeps popping up in the region's sugarcane fields every year.
Millhollon is exploring this biological approach to weed control at the
Sugarcane Research Unit, operated in Houma, La., by the Agricultural
Research Service, chief scientific agency of the U.S. Department of
In the lower Mississippi Delta region of southern Louisiana, where
Millhollon's research takes place, cane growers typically rely on chemical
herbicides to rid their fields of the pesky grass. One concern, however, is
the potential build-up of chemical residues in the environment. Another is
cost: Cane growers can spend up to $50 per acre applying chemical controls.
Though a good sugar crop can defray the expense, each new season is met by a
fresh contingent of the weed, necessitating another round of herbicide.
To break the cycle, Millhollon has sought to develop the smut fungus into a
so-called mycoherbicide. The trick: getting the fungus to infect the whole
plant, weakening it and its prolific seed-producing machinery.
In greenhouse experiments, Millhollon injected a smut spore solution
directly into the weed's tissues, causing infection rates of 75 to 85
percent and seedheads resembling a dark, crumbly mass. In a more practical
approach, Millhollon formulated the fungus into a mycoherbicide, spraying it
onto the weed in field plots. Though 50 to 80 percent became infected, the
treatment didn't protect the plot's cane crop as well as conventional
herbicides. Now, Millhollon is eyeing ways to give the fungus a helping
hand, including breeding it with other Sphacelotheca that are more effective
at infecting Johnsongrass.
A longer article about smut, the fungus, appears in the May issue of
Agricultural Research magazine at:
Scientific contact: Rex Millhollon, ARS Sugarcane Research Unit, Houma, La.,
phone (504) 853-3174, fax (504) 868-8369, Rmillhol@nola.srrc.usda.gov.
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