Bulletin number 3, 6/8 – 6/14/20

This week late blight was found in western Washington state near Mt Vernon in a home garden. Late blight has not yet been reported in Idaho. Download the spore trapping potato data here and the sugar beet spore trapping data here. Both excel spread sheets require a password to open then. Email us to request access to the data.


Although weather conditions associated with an elevated risk of late blight were observed in Idaho, at Parma (4 days), Grandview (3 days), Glenns Ferry (3 days) and Rupert (3 days) late blight spores have not yet been detected in Idaho. However, if your crop has reached row closure and you are in any of these areas you should be vigilant for signs of the disease. It is especially important to scout low lying areas where moisture and dew accumulates longer in the morning and tree lines along the edges of fields which provide shade and increase humidity levels.

No spores of Sclerotinia sclerotium (white mold) or Alternaria solani (early blight) were detected this week. However, Alternaria solani has been isolated from potato leaves in southwest Idaho, although the incidence was at very low levels in the field.

PVY was detected in bucket traps at Parma this week.

Sugar beet

Spores of Erysiphe betae (powdery mildew) were detected at spore traps in Adrian (4 days), Parma (3 days), Glenns Ferry (2 days) and Kimberly (5 days). No spores were detected at American Falls. Presently weather conditions are not conducive for powdery mildew. Growers should consider increasing scouting efforts and be prepared to commence spray programs if conditions become conducive for the disease in the next few weeks.