Manage pigweed early for best results

In Southwest Farm Press

by Muthu Bagavathiannan, Josh McGinty, Vijay Singh, Peter Dotray , Texas A&M AgriLife

Palmer amaranth and waterhemp are two pigweed species that have become problematic in row crop production fields in Texas. Palmer amaranth is widespread in the High Plains, Rio Grande Valley, Coastal Bend and Central Texas regions, whereas waterhemp is predominantly found in the Upper Gulf Coast as well as the Blacklands regions.

Herbicide resistance in these two species is an emerging issue and Extension specialists have emphasized the need for diversifying weed management tactics to prevent or delay resistance. Because pigweeds produce enormous amounts of seeds, preventing seed production from the escapes is a critical component of sustainable resistance management. Research has shown that a single Palmer pigweed plant can produce in excess of 1.5 million seeds under good growing conditions. Continue reading

New gene for atrazine resistance identified in waterhemp

Waterhemp has been locked in an arms race with farmers for decades. Nearly every time farmers attack the weed with a new herbicide, waterhemp becomes resistant to it, reducing or eliminating the efficacy of the chemical. Some waterhemp populations have evolved resistance to multiple herbicides, making them incredibly difficult to kill.

Adding to the challenge is the fact that waterhemp can evolve resistance in at least two ways. In target-site resistance, a gene mutation changes the protein that the herbicide is designed to attack. With an ill-fitting protein binding site, the herbicide becomes ineffective. The plus side of target-site resistance is that it is relatively easy to identify using standard lab procedures. Continue reading

Diversity is necessary in weed control

in Southwest Farm Press

South Texas, or coastal Texas, is a unique region of the greater Southwest, marked by a sub-tropical climate, unique soils and a host of both advantages and disadvantages when it comes to agriculture.

The warmer climate allows for an extended growing season, and its relationship with the tropical Gulf of Mexico offers some clear advantages, like seasonal rains, but also unique challenges, not the least of which is an environment conducive to the rapid growth and propagation of noxious and damaging weed varieties. Continue reading

Missouri research study finds waterfowl transports pigweed seeds

In Delta Farm Press

by David Bennett

It’s that time of year when the migration of waterfowl has begun and hunters unlock the gun cabinet and pull on camo. It turns out those wonderful ducks may be carrying more than the odd band and a desire for warmer climes.

Is the rapid spread of herbicide-resistant pigweeds in the Mid-South at least partially attributable to the flyway? A recent study out of Missouri says it is quite likely. Continue reading

Multiple herbicide resistance becoming problem for Southern farmers

In Delta Farm Press (with a video)

Farmers in the Mid-South and Southeast have spent a lot of money – and, in some cases, have lost entire fields – because of the development of resistance to glyphosate in prolific seed-producing weeds like Palmer amaranth or pigweed.

But how much will it cost them in added herbicide and labor expense and crop losses when weeds like pigweed or common waterhemp develop resistance to more than two or three or even more herbicide modes of action?

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Advice from weed resistance expert: Try diversity

From Southeast Farm Press

Renowned weed scientist Steve Powles, having had to find solutions and work-arounds in resistant weed-infested crops in his native Australia, has tried to prepare American producers for their own burgeoning resistance problems.

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New, resistant pigweed hybrid confirmed in Mississippi

From Delta Farm Press

At this point, the confirmation of a new glyphosate-resistant weed is unlikely to raise eyebrows. However, nonchalance is hardly the suitable reaction when considering the implications of what USDA-ARS researchers have uncovered in a Mississippi cotton field in Lafayette County.

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