Introduction
Ground Ivy, also called Gill-over-the-ground and Creeping Charlie is a common weed in Ontario [1]. It grows by forming dense patches, which crowd out native plants [1]. The plant flowers from March to July and spreads primarily through creeping stems (stolons) and forms shallow roots near the base of the plant [1]. It is difficult to control because root and stolon fragments regrow from fragments remaining in the soil if the plant is manually pulled out [1].
Control method: nitrogen fertilizer
A study by Kohler, Throssell, and Reicher (2004) [2] found that ground ivy can be controlled through nitrogen application. In their study, they tested different amounts of nitrogen at different times of the year, and found that all application schedules that they tested were effective in reducing the amount of ground ivy cover by as much as 32%. They used nitrogen in the form of urea and sulfur coated urea. Iin one condition, they applied 196 kg per hectare of nitrogen across three applications in the spring, summer, and fall (33% or 65 kg per application). One year later, they found a reduction of 24% in ground ivy in the area.
Note: 196 kg per hectare was seen as a reasonable application ratio for their product, but since nitrogen fertilizers can be different, it's best to use the application ratios recommended by the manufacturer for turf. The ground ivy population likely was reduced by the increased competitiveness of the Kentucky Bluegrass in the study. These results may not be replicated with other turf types.
Recommendation: if you have Kentucky Bluegrass, applying a three times a year, manufacturer-approved nitrogen schedule can help reduce the population of ground ivy in your turf.
All of the above information comes from #2
Control method: Fiesta
Fiesta method: in this study, researchers applied fiesta on multiple plots of land at two addresses. Each plot measured 4 x 4 ft. Ground Ivy coverage was 2-10% on each plot. Fiesta was mixed at a rate of 5 ounces per gallon and applied at a rate of 10 gallons per 1,000 square feet. One application was done in the 3rd week of June, and another 2 weeks afterwards.
Results: After the first application, some plots saw very impressive kill rates. 3 weeks after application at one plot saw a 91.7% drop in ground ivy coverage. At other plots, the results were less impressive (18.2% drop) and the researchers concluded that it was likely the low light levels which negatively affected the kill rate. However, after a 2nd application, 3 weeks afterwards, the kill rate rose to 93%-100% of the total ground ivy population.
Recommendation: purchase and use Fiesta according to manufacturer instructions.
Sources:
https://www.invasive.org/alien/pubs/midatlantic/glhe.htm [1]
Article reference: Cultural and chemical control of ground ivy (kohler, Throssell, and reicher 2004) [2]
https://ecommons.cornell.edu/server/api/core/bitstreams/1e3b1971-b157-4798-a2aa-0e744c938be8/content [3]