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Better weed management is essential

By Staff | Jan 18, 2014

DR. MIKE OWEN, an ISU Extension weed specialist, speaks to a Jan. 6 audience in Sheldon about herbicide resistant weeds.

SHELDON – Managing ahead of resistant weeds, rather than reacting to them, was the Jan. 6 message of Dr. Mike Owen, an Iowa State University weed specialist, to an audience of more than 140 at the Crop Advantage Series.

The event was held at the Northwest Iowa Community College in Sheldon.

Dr. Elwynn Taylor, ISU’s climatologist, told attendees they can brace for another two decades of volatile weather, with 2025 looking to be akin to the 1930s Dust Bowl.

Explaining it is necessary for farmers to develop a weed management program in advance, and not just attacking resistant weeds, Owen said: “Weeds will adapt, you must know your herbicide action group.”

There are numerous ways for weed seeds to migrate, whether through livestock manure spread on a field or the combine sowing them liberally at harvest.

According to Owen, waterhemp, horseweed – also known as marestail – and giant ragweed have developed herbicide resistance in Iowa.

In fact, he said, 30 percent of Iowa’s weeds are resistant to various herbicides, so a coordinated program of chemicals used to burn weeds down is necessary.

Due to the continual use of the same herbicide each year contributed to weeds developing resistance to glyphosate, the active element in Round-up herbicide.

Owen said a diversity of herbicide protocols need to be used to keep or slow a weed’s capability of developing resistance, Owen said.

He said the U.S. leads the word in prevalence of resistant weeds.

He said Dow Chemical Co. has developed a soybean trait that is resistant to dichlorophenoxyacetic acid, or 2,4-D, and is meant as an alternative to Round-Up Ready soybeans.

Weather outlook

In noting that Jan. 6’s windchill was at minus-44 degree, Elwynn Taylor said the Arctic Circle was actually above freezing that day.

He said the Midwest was sustaining its fifth polar breakout of the winter.

“Typically there are two to four polar outbreaks in an average winter,” Taylor said, “and we are already at five, so I believe we are heading in the direction of a harsh winter which can average seven outbreaks.

“A harsh winter can be measured by snow, cold or both of these to get this classification “

He showed the jet stream is on a 20-year cycle, adding that although the weather seemed unusually harsh, 2014 shows it to be only during winter.

Going deeper into this subject, he said the Corn Belt goes through a drought every 19 years, with each cycle getting a bit worse.

A big part of the weather record is recorded in tree rings, he said, which are wide or narrow depending on available moisture in any given year.

If history is correct, Taylor said, 2025 will be the harshest yet and will be the next Dust Bowl. This is being monitored by weather stations scattered across Iowa.

“Agriculture directly impacts climate change,” said Taylor, adding that climate change is not crazy.

Carbon dioxide is increasing because people are using fossil fuels faster than earth can process it

Increasing the use of biofuels will help, he said, what one burns goes into the atmosphere, and gets used the next year during the growing season.

The United States has dropped it’s energy consumption below what it was in 1972, Taylor said, “but the fact is that the more money you have the more energy you consume.”

He said overnight temperatures are not dropping as low during the growing season as they do normally, which creates need for more moisture and lowers the corn

Looking forward to 2014, if everything goes exactly as predicted for the next 11 months, the average nationwide corn yield should be 3 percent above 2013’s yield to 165 bushels per acre.

He said the USDA’s crop forecast has only been correct four times since 1965 as the weather had only been average four times.

Taylor said the differences in an El Nino weather pattern – cooler and wet – creates higher corn yields and lower prices, and a La Nina pattern – hotter and dryer – trims yields and drives up prices.

Although indications show 2014 weather patterns appear to be neutral between the two extremes, the climate risk for agriculture is worse during the next 20 years.

The Crop Advantage Series is specifically tailored for producers and agribusinesses.

This series is jointly presented by Iowa State University and the Iowa Soybean Association.

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