Using Lontrel to Help Manage Glyphosate Resistant Canada Fleabane in Tender Fruit

Kristen Obeid, OMAFRA Weed Specialist – Horticulture

March 30, 2020

Canada fleabane (also known as horseweed or marestail) is a winter annual weed. Its seed will either germinate in late summer and over-winter, or in the spring.

Effective management strategies should focus on removal of seedling plants both in the fall and in the early part of spring. Since small fleabane plants are not deeply rooted, many different types of tillage implements provide good control of this weed.

Glyphosate resistant Canada fleabane has been confirmed in 30 counties throughout the province.  Some counties also have multiple resistant Canada fleabane which is resistant to both glyphosate (Group 9) and ALS (group 2) herbicides.  It is finding its way from fields of corn, soybeans and wheat into all horticulture crops at an amazing rate.  Therefore, we need to know what management options are available to prevent the further spread of this multiple resistant weed.

The following table provides herbicide options for managing Canada Fleabane:

Current Registered Herbicides That Provide Good Control of Canada Fleabane 

Crop	Pre-Emergence  Spring1	Post-Emergence	Pre-Emergence Fall1
Apricots	Alion (G29), Chateau (G14), Sencor (G5)	2,4-D (G4), Basagran2 (G6) glyphosate (G9), Ignite (G10), Lontrel (G4)	Alion (G29), Chateau (G14), Sencor (G5)
Cherries/Plums	Alion (G29), Chateau (G14), Sencor3 (G5)	2,4-D (G4), Basagran2 (G6) glyphosate (G9), Ignite (G10), Lontrel (G4)	Alion (G29), Chateau (G14), Sencor3 (G5)
Peaches	Alion (G29), Chateau (G14), Sencor (G5)	2,4-D (G4), Basagran2 (G6) glyphosate (G9), Ignite (G10), Lontrel (G4)	Alion (G29), Chateau (G14), Sencor (G5)
Pears	Alion (G29), Chateau (G14), Sencor (G5)	2,4-D (G4), Basagran2 (G6) glyphosate (G9), Ignite (G10), Lontrel (G4)	Alion (G29), Chateau (G14), Sencor (G5)

G= Herbicide group

¹ All pre-emergence herbicides can be tank-mixed with glyphosate (G9) or Ignite (G10) if Canada fleabane is emerged at time of application.

² Non-bearing trees only

³ Cherries only.

NOTE: Control of Canada fleabane is best with pre-emergence herbicide applications.  Control with post-emergence applications will always be best on small plants.  Most label rates provide control at less than 20 leaves or 15 centimeters (6 inches), see Figure 1.

 SPECIAL NOTES:

1. Alion does not have Canada fleabane on the Canadian label; however, it is on the U.S. label.
2. Sencor does not have Canada fleabane on the label; however, many field trials in soybeans suggest adequate control when tank-mixed with glyphosate.
3. Basagran has Daisy fleabane on the label, but not Canada fleabane.
4. Lontrel does not have Canada fleabane on the label; however, it does have a blanket statement “for the control of broadleaf weeds including vetch species”. Canada thistle and perennial sowthistle (topgrowth) are also labeled.

RECOMMENDED HERBICIDE PROGRAM IF GLYPHOSATE RESISTANT CANADA FLEABANE IS YOUR TARGET WEED

1. Alion + Ignite in the fall
2. Chateau + Sencor in the early spring
3. Lontrel in the spring on fleabane rosettes that are less than 6 inches (15 cm) and were not controlled by application 2 above.

Non-chemical means of controlling glyphosate resistant Canada fleabane are tilling small rosettes regularly, mowing larger plants, or mulching in the spring.  A commitment to using Integrated Weed Management – a combination of chemical, mechanical and cultural weed control strategies throughout the growing season will help reduce herbicide resistant weed species.

If you think you have glyphosate resistant Canada fleabane in your tender fruit orchards, we can test it for you.  Please contact me:

Kristen Obeid

kristen.obeid@ontario.ca

519-965-0107 (cell and text)

@WeedProfesh (twitter)

We just need to collect leaf tissue from 10 different Canada fleabane plants in your orchard.  Results can be completed within 2 -10 days. It’s always easier to manage something once you know what you are dealing with.