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Late Blight Update (8/03/17)

Late blight has been confirmed in a commercial potato field in Pembina County and Nelson County, ND. The genotype from Pembina County is US23.

Late Blight Update

Late blight has been confirmed in a commercial potato field in Pembina County and Nelson County, ND. The genotype from Pembina County is US23. Late blight has been reported in other areas, but not confirmed. Home gardens can be a source of late blight because tomatoes and potatoes are generally not treated with fungicide. Tomatoes are susceptible to the US23 genotype. Because of the widespread findings of late blight, we recommend that all potato fields in northeastern ND should be thoroughly scouted for the presence of late blight. Growers in areas where late blight is present should apply a specialty fungicide with strong activity against late blight, such as Orondis, Revus Top, Ranman, Omega or Gavel.

All areas bordering the Red River Valley north of Interstate 94 have exceeded the late blight threshold value of 15. This indicates that conditions have been favorable for late blight infection if inoculum is present. Growers in this area should be scouting fields and applying fungicides, concentrating on areas of the field that stay wet longer such as along tree lines and low areas where water accumulates.

Please send suspect late blight samples to NDSU so we can identify genotypes and monitor the spread and location of late blight. Remember that late blight is a community disease and to notify your neighbors if late blight is found. Please see the NDSU Extension bulletin Late Blight in Potato for pictures and more information on late blight.

 


Andy Robinson

NDSU/U of M Extension Potato Agronomist

 

Gary Secor

NDSU, Plant Pathologist

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