Nipplewort Control in Winter Wheat

 

Question: “Have a customer with a no-till rotation that has Nipplewort. A lot of it. We found some pretty decent options for most crops in the rotation to clean it up before planting, but he’s got some in his wheat this year too. What would be our best option to take a swing at it in wheat?”

Background: For a brief primer on nipplewort, I would refer you to the December 2014 issue of Country Guide, where I provided an overview of what we knew about managing nipplewort at the time Pest patrol:controlling nipplewort.

Answer: Sometimes it takes a long time to find a good solution for a weed that is difficult to control. In the case of nipplewort infesting cereal crops, it has taken so long that if nipplewort was a person, it could legally vote.

First off, Nipplewort is not an overly common weed species. Finding fields with uniform and relatively dense stands of this weed has proven challenging, and therefore difficult to do replicated herbicide trials. For the farmers that have it though, it does negatively affect crop production, especially in winter cereals where it typically germinates in the fall and becomes quite large by the time postemergence herbicides are applied in the spring. Secondly, nipplewort is tolerant to a lot of herbicides. Therefore, you need to screen a lot of herbicides and tank-mixes in order to find promising treatments that you would want to test under field conditions.

Dr. François Tardif, Peter Smith (University of Guelph) and I started this process in 2002 and we certainly were able to identify herbicides that didn’t work, but thankfully we found a handful of products that gave us reason for optimism, we just needed to tweak some treatments and look at them under more field sites. Finally during the 2020 field season, we have more confidence that one tank-mix in particular, Lontrel XC + Refine SG + non-ionic surfactant, gives us the best opportunity to control nipplewort. We also discovered that some of the newer herbicides that weren’t available back in 2002, aren’t particularly effective (Table 1).

Table 1. Visual control of nipplewort at 6 weeks after the application of three herbicides labelled for use in winter wheat during the spring of 2020.

TreatmentRates/acreVisual control
Pixxario A + Pixxaro B123 mL + 236 mL10%
Infinity FX400 mL50%
Lontrel XC + Refine SG100 mL + 12 g + 2 L/1,000 L95%

 

Figure 1. The untreated control plot.

 

Figure 2. Nipplewort control at six weeks after an application of Pixxaro herbicide.

 

Figure 3. Nipplewort control at six weeks after an application of Infinity FX herbicide.

 

Figure 4. Nipplewort control at six weeks after the tank-mix application of Lontrel XC + Refine SG + non-ionic surfactant.