Targeting Weed Seeds In-Crop: A New Weed Control Paradigm

The widespread evolution of multiple herbicide resistance in the most serious annual weeds infesting cropping fields has forced the development of alternative, non-chemical weed control strategies, especially new techniques at grain harvest, says a recent Weed Science Society Of America (WSSA) publication.

Harvest weed seed control (HWSC) systems target weed seed during commercial grain harvest operations and act to minimize fresh seed inputs to the seedbank. These systems exploit two key biological weaknesses of targeted annual weed species: seed retention at maturity and a short-lived seedbank. HWSC systems, including chaff carts, narrow windrow burning, bale direct, and the Harrington Seed Destructor, target the weed seed bearing chaff material during commercial grain harvest. The destruction of these weed seeds at or after grain harvest facilitates weed seedbank decline, and when combined with conventional herbicide use, can drive weed populations to very low levels. Very low weed populations are key to sustainability of weed control practices. Here we introduce HWSC as a new paradigm for global agriculture and discuss how these techniques have aided grain cropping and their potential utility in global agriculture.

Current Weed Control Paradigm in Global Field Crops: Target Weed Seedlings

The current dominant paradigm for weed control in field crops is PRE or early POST herbicides to remove weed seedlings in young, establishing crops. Crop yield is securedby controlling weed seedlings during this critical ‘‘weed free period’’during which crop plants are particularly vulnerable to weed competition.

However, despite herbicide use, some in-crop weeds inevitably escape herbicide control for a range of reasons (eg. adverse environmental conditions, insufficient herbicide, herbicide resistance, delayed emergence) and in the great majority of situations there is no other feasible, practicable method of controlling these surviving weeds. Hence, these weeds survive to maturity with the crop and produce significant quantities of seed which sustain or build a viable weed seedbank.

It is the ongoing, annual production of weed seeds that perpetuates and amplifies many crop-weed infestations in global field crops. Annual weed seedbank replenishment ensures that each year high weed numbers emerge and are herbicide treated, with the inevitable risk of resistance evolution. It has long been recognized that alternate weed control strategies are needed to alleviate intense herbicide selection.

Globally, there are few suitable alternatives to herbicides and even when alternatives (eg. cultivation, crop competition, delayed seeding) are considered, the focus remains on preventing weed seedlings from interfering with early crop growth. However, weed adaptations, such as seed dormancy, in response to changes in cultivation and cropping practices, have already occurred in several annual species including annual ryegrass, wild oats, brome grass and barley grass.

These evolutionary adaptations in response to a selection pressure further highlight the consequences of neglecting seed production and seedbank replenishment by weeds surviving early season control practices. Clearly, new tools are needed that complement early season weed control techniques by targeting annual weed seed production.

New Weed Control Paradigm: Harvest Weed Seed Control (HWSC)

Widespread multiple herbicide resistance in the very important weeds, annual ryegrass and wild radish, of Australian cropping has forced the development of additional weed control strategies.
Knowledge that the major proportion of an in-crop annual ryegrass population results from the previous season’s seed production led to a focus on minimizing weed seed production.

The biological attribute of seed retention at maturity in annual ryegrass, wild radish, and several other annual crop weed species, means that seeds are attached to the upright plant enabling the weed seeds to be collected (harvested) during grain crop harvest. For example, in field crops a large proportion (up to 80%) of total annual ryegrass seed production can be collected during a typical commercial grain harvest. These weed seeds enter the front of the grain harvester, are processed, and exit the grain harvester in the chaff fraction. An irony is that these ‘‘harvested’’ weed seeds are evenly redistributed across the crop field to become future weed problems.

Thus, grain crop harvest presents an opportunity to target weed seed production, thereby minimizing replenishment/increase of the weed seedbank. As outlined below, harvest weed seed control (HWSC) systems have been developed in Australia to target and destroy weed seeds during commercial grain crop harvest, minimizing weed seed inputs into the seedbank.

SOURCE: Weed Technology, 2013, Weed Science Society Of America, Michael Walsh, Peter Newman and Stephen Powles. Academic citations removed have been removed.

Go here to read the full academic review as a .pdf file.

Topics:

Leave a Reply

Crop Inputs Stories

Young corn plants in soil
Crop InputsFortenza Insecticide Seed Treatment Receives EPA Registration
May 25, 2017
Fortenza seed treatment insecticide from Syngenta has received registration approval from the U.S. EPA for use on corn and cotton Read More
Photo credit: The United Soybean Board/The Soybean Checkoff.
Seed/BiotechKansas State University Researchers Find New Pathogens in Soybean Seeds
May 24, 2017
A single seed seems so simple. Put it in the ground, give it some care, and you’ve soon grown food. Read More
Soybean Field
HerbicidesNew Dicamba Herbicide Premix Coming Soon from Syngenta
May 24, 2017
Syngenta has announced the name of its new herbicide featuring the active ingredients of S-metolachlor and dicamba. Upon registration by Read More
FungicidesSyngenta Launches New Seed Treatment Fungicide
May 22, 2017
Syngenta has announced the launch of PLENARIS seed treatment fungicide for the control of downy mildew in sunflower. PLENARIS contains Read More
Trending Articles
Migrant farm workers
LegislationTrump: Immigration Crackdown Won’t Impact U.S. Agriculture
May 16, 2017
President Donald Trump said he would seek to keep his tough immigration enforcement policies from harming the U.S. farm industry Read More
AGCO Ratliff featured
Eric SfiligojRemembering Robert Ratliff
May 15, 2017
With all the fast-paced happenings in agriculture this spring, with multiple mergers in the works and planting season in full Read More
Case sprayer nozzle closeup
EquipmentSpray Application: A Nozzle Renaissance
May 2, 2017
If you had asked four-decade ag veteran Mark Bartel, President of Wilger Inc., just a few years ago what lay Read More
ManagementWashington Update, Dow-DuPont Earnings, and the Passing of an AGCO Legend
April 27, 2017
Editors Paul Schrimpf and Eric Sfiligoj talk about the latest Beltway news, crop protection company 1st quarter numbers, and the Read More
Crop InputsFlying Under the Radar No More, FMC Goes Big
April 13, 2017
Describing FMC as “under the radar,” admittedly, is probably a stretch. But in a snap of the fingers, FMC upped Read More
Young Corn Plants
Crop NutritionStill Hunting Yields
April 1, 2017
There’s no denying it — the agricultural marketplace today is undergoing a fundamental shift in fortunes. Not too many years Read More
Latest News
ManagementTrip Report, PSM R.I.P, and Ag’s Reaction to Federal Bu…
May 25, 2017
Editors Paul Schrimpf and Eric Sfiligoj talk about their recent travels, the end for Process Safety Management (PSM), and how Read More
Corn soil
LegislationARA Member Testifies Before Senate Ag Committee
May 25, 2017
Agricultural retailers stand on the front-lines of the American economy. As trusted advisors to America’s farmers, ag retailers are uniquely Read More
Young corn plants in soil
Crop InputsFortenza Insecticide Seed Treatment Receives EPA Regist…
May 25, 2017
Fortenza seed treatment insecticide from Syngenta has received registration approval from the U.S. EPA for use on corn and cotton Read More
ManagementFarm Market iD’s Agriculture Database Now Covers More T…
May 25, 2017
Farm Market iD, farmmarketid.com, has announced the release of its 2017 Annual Update of its farm and land database. The Read More
Food IT Fork-to-Farm
Precision AgThe Mixing Bowl Event Connects Technology, Food, and Ag…
May 24, 2017
For the fourth consecutive year, The Mixing Bowl presents FOOD IT, under the theme “Fork to Farm.” Action-oriented entrepreneurs, industry Read More
Photo credit: The United Soybean Board/The Soybean Checkoff.
Seed/BiotechKansas State University Researchers Find New Pathogens …
May 24, 2017
A single seed seems so simple. Put it in the ground, give it some care, and you’ve soon grown food. Read More
Soybean Field
HerbicidesNew Dicamba Herbicide Premix Coming Soon from Syngenta
May 24, 2017
Syngenta has announced the name of its new herbicide featuring the active ingredients of S-metolachlor and dicamba. Upon registration by Read More
Eric SfiligojMonsanto ‘Picks Its Battles’ by Nixing Deere Deal
May 23, 2017
Having been in the trade journalism game since the mid-1980s, I remember several watershed moments during my career. One of Read More
FungicidesSyngenta Launches New Seed Treatment Fungicide
May 22, 2017
Syngenta has announced the launch of PLENARIS seed treatment fungicide for the control of downy mildew in sunflower. PLENARIS contains Read More
Corn close up
Crop InputsMonsanto’s First HPPD Herbicide Garners EPA Appro…
May 19, 2017
Monsanto announced today that EPA has federally approved Harness MAX Herbicide, the first herbicide in the Monsanto portfolio to provide Read More
ManagementPrecision Planting Deal, China Developments, and Enviro…
May 18, 2017
Editors Eric Sfiligoj and Dan Jacobs discuss the latest news on John Deere’s now dead deal for Precision Planting, China’s Read More
Soybean aphid leaf
InsecticidesMulti-state Research Reveals IPM Best Option for Treatm…
May 17, 2017
About 89.5 million acres of soybeans will be planted across the U.S. in 2017 — a record high, according to Read More
GROWMARK-2017-Interns
CropLife 100GROWMARK Names 2017 Summer Interns
May 16, 2017
Forty-two college students are exploring agricultural career opportunities this summer as GROWMARK interns. They are working at FS member cooperatives Read More
Migrant farm workers
LegislationTrump: Immigration Crackdown Won’t Impact U.S. Ag…
May 16, 2017
President Donald Trump said he would seek to keep his tough immigration enforcement policies from harming the U.S. farm industry Read More
Flooded corn in Indiana
FertilizerBoth Wet and Dry Conditions Threaten Nitrogen Loss
May 15, 2017
The weather is notoriously unpredictable, leading to challenges for planting, harvesting and applying the nitrogen (N) your corn crop needs. Read More
farmer Kip Tom
Precision AgAg Tech: On the Cusp of Something Big?
May 15, 2017
The investment and ag-tech sectors’ continuing courtship of agriculture, smoldering for three or four years now, was well in evidence at Read More
AGCO Ratliff featured
Eric SfiligojRemembering Robert Ratliff
May 15, 2017
With all the fast-paced happenings in agriculture this spring, with multiple mergers in the works and planting season in full Read More
Greg Musson, Gar Tootelian
ManagementOpinion: Shaking Your Perspective in Ag Retail
May 12, 2017
Some of you I’m sure have encountered our recently retired salesman extraordinaire, Dan Bellanger. He worked in the industry for Read More