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Common Mullein Control: Herbicide Choice and Application Timing

Common Mullein Control: Herbicide Choice and Application Timing
By Nevin Lawrence and Mitchell Stephenson
 
Common mullein (Verbascum thaspsus L.) has been a problematic invasive weed in Nebraska for a number of years. In in the past two years however, there has been a greater concern among ranchers and landowners in central and western Nebraska about controlling common mullein. Several articles have been previously posted on CropWatch regarding the biology and management of common mullein, and common mullein herbicide options are included in the annually updated Guide to Weed Management in Nebraska.
So why the recent increasing interest in common mullein? The past few winters have favored survival of weed species that overwinter, including winter annuals such as cheatgrass and marestail (horseweed), and common mullein a biennial. Common mullein seed germinates in the spring and spends the first year in a vegetative rosette. After surviving the winter in this vegetative form, common mullein bolts and moves into a reproductive growth habit to later produce seed. Mild, wet winters help ensure good germination the following year for new seedlings and good winter survival of plants entering the second year. The last few winters have benefited common mullein. Common mullein can especially thrive on sites that have considerable amounts of plant residue at, or near the soil surface.
 
Herbicide Choice and Application Timing
 
Another reason for greater interest in common mullein is a frustration among some stakeholders who are not achieving effective control of common mullein. Often stakeholders have been disappointed in the level of control a particular herbicide product provides, and they want to know what might work better. So what product should you use to control common mullein?
 
Effective weed control in range, pasture, and CRP depends on selectivity and timing. Selectivity simply means the herbicide you choose to use will control the weed you wish to target. Timing refers to when an herbicide will be applied. In selecting an herbicide for common mullein control, there are a lot of options (Table 1).
Table 1. Herbicide products labeled for common mullein control.
Trade NameCommon NameRate (per acre)Timing
Products With a Single Active Ingredient
Tordon®Picloram1 to 1.5 ptsBefore bolting
Milestone®Aminopyralid5-7 fl ozBefore bolting
Method®240SLAminocyclopyrachlor4-8 fl ozNot specified
Escort®XPMetsulfuron Methyl1 – 2 ozNot specified
Telar®XPChlorsulfuron1 – 2.6 ozNot specified
Products With Multiple Active Ingredient
Graslan®LPicloram + 2,4-D2 2/3 ptsBefore bolting
GrazonNext®HLAminopyralid + 2,4-D1.5 to 2.1 ptsNot specified
DuraCor™Aminopyralid + Florpyrauxifen-benzyl16 to 20 fl ozNot specified
MezaVue™Picloram + Aminopyralid + Fluroxypyr32 fl ozBefore bolting
Chaparral™Aminopyralid +
Metsulfuron methyl
2 oz
2.5 to 3.3 oz
Before bolting
After bolting, but while the plant is less than 12” in height.
Cimmaron® MaxMetsulfuron Methyl + Dicamba + 2,4-DPart A 0.25 oz + Part B 1 ptNot specified
Cimmaron® PlusMetsulfuron Methyl + Chlorsulfuron0.625 to 1.25 ozNot specified
Pastora®Metsulfuron Methyl + Nicosulfuron1 ozNot specified

 

 
When choosing a herbicide product for use in rangeland or CRP, picking a product with a mixture of more than one active ingredient (Table 1) (for example: Graslan®L, GrazonNext®HL, DuraCor™) is a safe bet as products with more than one active ingredient may control a larger number of broadleaf weeds and potentially offer a larger application window compared to a single active ingredient product. However, all the products listed in Table 1 do claim to control common mullein. When timing of application is specified on the various product labels, the recommendation is always before bolting.
 
Common mullein bolts in the early summer of its second year of growth. Applying an herbicide after bolting likely will control first year common mullein that is present but miss the second-year mullein that has already bolted. A fall application can control common mullein before it overwinters, but the herbicide likely will not persist in the soil into the following spring when new seedlings emerge. A spring application in April or May is generally the best time to control common mullein as you can control both the newly emerged weeds, and those which overwintered before they bolt.
 
Which Common Mullein Products are Best?
 
So why have some stakeholders observed poor mullein control even when using registered products? Either the application was not well-timed or some labeled products do not provide good enough control. In response to stakeholders, the Panhandle Range Management and Integrated Weed Management Programs put out a trial in April of 2020 to test which herbicide products are providing the best control of common mullein. Herbicides were applied on April 21st, after spring germination of first year common mullein had started but before the second year mullein had bolted.
Table 2. Product evaluated in common mullein field trial.
Trade NameCommon NameRate (per acre)
Rugged®2,4-D1 qt
Banvel®Dicamba1 qt
Tordon®Picloram1 pts
Milestone®Aminopyralid7 fl oz
Method®240SLAminocyclopyrachlor8 fl oz
Escort®XPMetsulfuron Methyl1 oz
Telar®XPChlorsulfuron1 oz
 
At the time of application, no common mullein plants were larger than 4” in height. Rather than use products with more than one active ingredient, the choice was made to only use standalone herbicide products (Table 2). Additionally, each herbicide was applied both with 0.25% v/v non-ionic surfactant (NIS), and as a separate treatment with 1% v/v crop oil concentrate (COC) added.
 
Results
 
Common mullein control was assessed in early August, after first year plants had germinated and second year plants had bolted. In non-treated plots, the average density of common mullein was 15 plants per yd2. 2,4-D and dicamba are not labeled for common mullein control, but were included as they are both commonly included in labeled herbicide product mixtures. 2,4-D provided poor control, only reducing mullein density by 22% and 29%, with NIS and COC respectively.
 
Dicamba however reduced common mullein density by 93% and 100% with NIS and COC, respectively. All other products, which are labeled for common mullein control, resulted in 100% common mullein control. There was no significant difference in the levels of control provided by labeled products. Product performance also was not affected the adjuvant (NIS or COC) used.
 
We chose to conduct this herbicide trial in April as it is an ideal time to control common mullein. Had the herbicide applications been delayed to late May, or June, there may have been more differences in common mullein control between herbicide products. However, by keeping the application timely (i.e. early in the growing season), we were able to control common mullein with all labeled products, and even with dicamba which is not recommended for common mullein control.
 
Figure 1. Three plots treated in April, photos taken in August. Top, non-treated check; middle, 2,4-D; and bottom, Milestone®.
 
Key Points
  • Multiple active ingredient products may offer greater flexibility over single active ingredient herbicides for rangeland and CRP application.
  • When an herbicide is applied is often more critical than what herbicide is applied when controlling common mullein.
  • Spring applications offer the best shot at controlling both first and second year common mullein.
Source : unl.edu

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Why Rob Saik is Trying to Build the World’s Most Connected Agriculture Network

Video: Why Rob Saik is Trying to Build the World’s Most Connected Agriculture Network

In a recent interview at the SeedLink Conference in Brandon, Man., Rob Saik, author, speaker, and CEO of AGvisorPRO, took a trip down memory lane, reminiscing about the beginnings of his career and what the future holds.

Graduating from the University of Alberta in 1983, Saik embarked on a journey that started in Brandon, Man. “I got a job with Elanko, got a U-Haul truck, threw everything I had into it, drove to the Victoria Inn, and lived there for three months while they tried to find an apartment for me to move into. So I started my career in Brandon,” Saik shared.

Fast forward to the present, Saik has evolved into an accomplished author and speaker, traversing the globe to engage in high-level discussions about the future of agriculture and the critical role it plays in feeding the world. Yet, despite his global presence, he finds himself back in Brandon, addressing a group of seed growers. But why? Saik emphasizes the fundamental importance of seeds, stating, “It all begins with a seed, doesn’t it?”

Reflecting on his own experiences as a farmer, Saik expresses his excitement when a planted seed germinates and evolves into a thriving crop. He underscores the significance of technology and breeding in seed development, recognizing the crucial role they play in ensuring farmers can propagate seeds, grow profitable crops, and contribute to global food security.

Saik delves into the challenges faced by the agricultural community, particularly the rapid pace of technological advancements. He believes that the key lies in connecting farmers to experts swiftly, boosting farmers’ confidence in adopting new technologies, and ensuring the timely implementation of these advancements. According to Saik, this approach is crucial for steering agriculture towards sustainability and profitability.

As Saik works on his upcoming book, tentatively titled prAGmatic, he sheds light on its central theme. “The thesis would be that I want to write a book that takes what the consumer wants, challenges what the consumer believes, and positions that against what the farmers can actually do pragmatically,” he explains. The book aims to bridge the gap between consumer expectations and the realistic capabilities of farmers, promoting sustainable intensification as the necessary path to feed the planet.

Looking ahead to 2024, Saik emphasizes the need for enhanced connectivity within the seed industry. He discusses his platform, AgvisorPro, which is designed to facilitate connections between farmers, experts, and companies in a way that transcends conventional social media platforms. Saik envisions a credible, connected agricultural network that goes beyond the noise of platforms like LinkedIn or Twitter.

In a passionate vision for the future, Saik imagines a tool for teachers that allows them to pose questions from students, answered by verified farmers and ranchers. This, he believes, would provide an authentic and valuable educational resource, connecting classrooms with individuals who truly understand the intricacies of agriculture.