Spotting Late Blight

The warmer days and cooler nights are prime conditioins for late blight. “… Late blight symptoms first appear as somewhat circular, water-soaked spots near the edge of expanded leaflets. These spots expand rapidly during moist weather to form irregular brown, dead areas. There is often a light green margin between the dead tissue in the center of the spot and the normal green tissue outside the spot. The real diagnostic feature of late blight is the white, downy-looking mold that develops at the margin of the spot on the underside of the leaflet. If the white mold is not obvious, remove the suspicious leaflet and put it in a plastic bag with a moist (rung out well, not sopping wet) paper towel for 24 hours to see if this symptom develops. If it does not develop, late blight is probably not the cause of the leaf spots you are seeing. …”

Late blight possible as warm days head into cooler nights.

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