Canadian Alberta officials look for additional herbicide options for seed alfalfa fields

The Group 14 herbicide Authority may be effective against kochia in seed alfalfa fields, according to early data from a southern Alberta plot trial, Canada.


Though not registered for use in alfalfa, the chemical killed kochia and outperformed Edge and Velpa. The latter two also showed good results. 


The findings may lead researchers to investigate further and possibly apply for the chemical to be registered for use in seed alfalfa crops.


“We were looking primarily for kochia control. This is an issue and we are looking for some more options,” Alberta Agriculture weed scientist Chris Neeser told an Alfalfa Seed Commission field tour July 23.


“With Chateau, we had our doubts about it, so as far as going ahead with seeking a registration that is a minor use label extension, we will probably put weight on trying to get the Authority label (for kochia).”


However, Authority has some restrictions for recropping, which growers will have to recognize if the product is labelled for seed alfalfa crop use.


“Its use in alfalfa may be limited to the second or third year at the most if you’re going up to five years. You don’t want to use it the last year,” Neeser said.


Chateau is registered for use in berry, vegetable and tree crops. 


It showed little kochia control in alfalfa in the plot trial.


“All three products, that being Authority, Edge and Velpar, were fairly good on kochia,” he said.


“Chateau not so much, no better than untreated, and that is across all the different tillage treatments.”


The plot trial northeast of Enchant also involved demonstrations of seven tillage implements. 


Growers agreed it was difficult to see differences between them upon visual inspection. 


However, weed counts showed each implement resulted in some level of reduction in dandelion and narrow-leafed hawksbeard. None of the tillage methods affected levels of Canada thistle or annual weeds.


Neeser said there are few herbicide options for seed alfalfa fields. The alfalfa stands for four or five years and is seeded sparsely to promote blossom and seed set. As a result, it vulnerable to weed infestation.