More precautions needed when spraying with dicamba and 2,4-D

From the Weed Science Society of America

New resistant soybean and cotton cropping systems based on the synthetic auxin herbicides give farmers new options for managing Palmer amaranth and other broadleaf weeds resistant to glyphosate. But scientists with the Weed Science Society of America (WSSA) say special precautions are necessary. Auxin herbicides are known to drift and to cause harm to sensitive, off-target broadleaf plants.

“Concerns about drift led the U.S. EPA to issue time-limited registrations for the auxin herbicides dicamba and 2,4-D of two years and five years respectively,” says Kevin Bradley, Ph.D., past president of WSSA and associate professor at the University of Missouri. “The approved product labels have considerable detail on management of drift and other risks and must be carefully followed to reduce off site movement. Unless growers show they can use these herbicides as labeled, the registrations could easily be revoked.” Continue reading

University of Illinois Plant Clinic announces Palmer amaranth seed ID and herbicide resistance plant tissue testing

Last summer, farmers in the Midwest got an unwelcome surprise after planting native seed on Conservation Reserve Program acres. Palmer amaranth is an aggressive and hard-to-kill weed. As a possible solution, some states declared Palmer a noxious weed, which prohibits its sale and transport.

The typical testing method involves growing a sample of seeds until the plants are large enough to be identified, but this is a slow and potentially unreliable process. Pat Tranel, molecular weed scientist at the University of Illinois, said growers are calling and telling him, their businesses are up in the air because of this.” Unless they have a way to certify their product is Palmer-free, they can’t sell it,” said Tranel. There is a company that tests individual seeds using DNA sequencing, but charges $100 per seed. Continue reading

New National Pest Alert for Palmer Amaranth released

A new National Pest Alert for Palmer Amaranth has been released. This pest alert has been approved by the national leadership of USDA NRCS to address the recent problems with Palmer Amaranth seed inclusion in wildflower and pollinator seed mixes. Ultimately, decisions must be made at the local level to address the issue of Palmer amaranth in pollinator habitats, field edges and conservation plantings.

http://ncipmc.org/action/alerts/palmer.php

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

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

Missed the Palmer amaranth webinar? Recording is in YouTube

On Wednesday, February 15, Muthu Bagavathiannan, specialist in weed ecology and agronomy, presented a new tool for consultants, extension specialists and agents, and growers to assist with management decisions regarding Palmer amaranth, named PAM. Based in Microsoft Excel, the tool allows the user to input their rotation schedule, chosen varieties and other management practices. From those entries, the tool calculates the amount of weed seed present over a 10-year period, as well as the economic gains or losses during that period. In addition, it calculates the risk of the combination of practices and allows the user to compare up to 6 different management scenarios. The tool calculates risk based on the amount of weed seed present, which has been concluded to be the main reason for pigweed-related crop failures. 

You can get to the tool from this link.

If you would like to see Dr. Bagavathiannan’s presentation, follow this link to the YouTube recording. During the 60-minute video, he demonstrates how to use the tool and how to interpret the results.

Tomorrow at 3 PM ET: Learn about a pigweed decision management tool

Herbicide resistance in Palmer amaranth (known as Palmer pigweed) is a serious issue in the Southern US and is spreading to several other states. Repeated use of a few herbicide mechanisms of action (MOA) without sufficient management diversity is the common cause of this resistance. A proactive resistance management strategy that integrates diverse chemical and non-chemical tools will help prevent/manage resistance and preserve the utility of available herbicide options.

This webinar provides a general overview and demonstration of a new Microsoft-Excel based decision support tool that guides informed decision making for effective management of this weed, with particular focus on soil seedbank management and profitability. Users can build their own management programs and see for themselves how effective their pigweed management program is, as well as overall economic outcomes associated with their options. This tool also predicts the likely risk of resistance for the management program built by the user.

Date and time: Wednesday, February 15, at 3 PM Eastern time Continue reading