Incidence of Ascochyta Blight in Peas and Lentils in Northwest ND

Scouting of pea and lentil fields in NW ND has revealed low incidence of Ascochyta Blight in lentils (Fig 1), and low to moderate incidence in field pea (Fig 2) so far this season, however, cool and wet conditions in the forecast may lead to increased incidence of this disease. 

If timed appropriately, fungicides can be effective for management of Ascochyta Blight and Canadian researchers recommend using the following guidelines for making a treatment decision (Fig 3):

• Scout the same 4 locations in your field every 3-5 days from V10 through bloom
• Assign points to stand, leaf wetness, 5 day weather forecast and disease severity. 
• If the total number of points exceed 65 AND disease symptoms are present, a fungicide treatment may be warranted.

Also available at this website: http://reducedtillage.ca/docs/Ascochyta_Scoring_System_2006.pdf

Note: These guidelines have not been specifically tested for conditions in North Dakota and should serve only as a reference. 

When scouting, remember that it is critical to distinguish this disease from Bacterial Blight, which will not respond to fungicide treatment. For information about distinguishing Ascochyta blight from bacterial blight of peas see the bulletin Mycosphaerella (Ascochyta) blight and bacterial blight of peas.  For more information about Ascochyta Blight refer to the June 2^nd article published this year in the Crop & Pest Report: Field Pea Diseases Review: Ascochyta /Mycosphaerella Blight.

Audrey Kalil

Plant Pathologist, NDSU Williston Research Extension Center