Dr. Edith Breburda
Madison/Wisconsin. The severe drought in the USA is the media topic. For some it seems incredible, even unethical, that the government still plans to use part of the corn harvest for the production of bio-fuels at the risk of global hunger. Many farmers are being forced to slaughter their animals because of a lack of feed. The United Nations has urged the USA to stop the ethanol production in face of the drought, to prevent elevated global food costs.
We already know that global consequences of the drought will be severe but agriculture is taking a second lethal punch. The extreme heat stress has weakened the cellular defense of 85 percent of the Midwest corn crop. This weakened state, coupled with sudden rains, has left the crop vulnerable to infection with corn smut (Ustilago maydis).
This pathogenic plant fungus causes gall formation on all above-ground parts of corn plants. Disfigured tissue develops into galls within days after infection. Most obvious are the tumor-like formation growing on corn cob.
The entire ear is sometimes replaced by the smut gall, which is filled with spore powder.
Large
galls are originated from individual infected kernels and might reach up to six
inches in diameter. People in Mexico and some hobby gardeners consider immature
galls as a delicacy and not as a disease.
Throughout most of the world, however, corn smut is seen as a troublesome disease of corn. In 1911 when smut was first reported in Barthust, New South Wales, Australia, the infected crop was destroyed and corn was not planted on that farm for a decade.
Just
as in the USA in 2012, losses to smut are increased in situations in which the
plant is already injured by an unusual long period of drought. With no genetic
resistance to the fungus, the disease is responsible for significant crop loss.
In the USA, smut is of greater economic consequence in sweet corn, where the
annual loss is up to 20 %. According to the National Corn Growers Association,
a study at the Danforth Plant Science Center of St. Louis, MO, reported a loss
of $1 billion in crop losses to corn smut in 2011.
The
damage increases in plants heavily fertilized with nitrogen. One recommendation
to control the disease is crop rotation, but genetically modified crops are
always planted in large monocultures and modern seed companies offer no other
options.
Corn
smut infested silage can affect animal health. A paper written in 1868 by Dr.
H. Burt, Amer. Homeop. Obs, observed
that pregnant cows fed with infected corn miscarried their calves eight days
later. The toxin is thought to be similar to Ergot, which was used for
obstetric purposes to produce perfectly regular intermittent uterine
contractions that induced labor. Given its history of inducing labor, Ustilago maydis was also used as
abortifacient.
See also youtube video on that topic
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