MOOSE JAW, Sask. – Repeated use of strobiluron fungicides to control ascochyta blight in chickpeas is leading to increasing resistance.
Penny Pearse, a crop disease specialist with the Saskatchewan agriculture ministry, said a study of fungal isolates collected between 2004 and 2006 found 68 percent were not controlled by Quadris and 50 percent were not controlled by Headline.
Quadris was registered in 2001 and resistance was first detected in 2003.
Samples collected by BASF, which markets Headline, also confirmed resistance. Besides Saskatchewan, the problem has been discovered in Alberta and North Dakota.
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Last year, isolates and agronomic information were collected from 53 Saskatchewan fields. The isolates are being tested for resistance, and preliminary results are expected by early May.
“Strobiluron products are still effective,” Pearse told producers attending a recent pulse workshop in Moose Jaw.
She said producers need effective fungicides and must manage strobiluron resistance by rotating the use of the products with another from a different chemistry, such as Lance, Bravo or Proline.
“Don’t apply more than two strobilurons per season,” she cautioned, whether applying it solo, such as Quadris, or in a tank mix such as Headline Duo.
Strobiluron should not be the last application of the season, she added, as a way to reduce the resistant isolates overwintering in the fungal population. The last application should be Lance, Bravo or Proline.
Pearse said she doesn’t know of any resistance discovered in lentils because the fungal population isn’t as diverse.
The agriculture ministry has produced a first draft of Scouting and Management of Ascochyta Blight in Chickpea with funding from Agriculture Canada’s Pesticide Risk Reduction Program.
Information on strobiluron resistance is contained in the booklet, along with other agronomic information designed to help manage the disease.
