Several diseases can affect tobacco seedlings in float beds. These include anthracnose, blue mold, collar rot, pythium root rot, damping off (soreshin), blackleg, and target spot. Pythium root rot and target spot usually are the most common. Let’s look at target spot today.
Target spot begins in localized areas and commonly occurs after the plant canopy has fully formed. Small, water-soaked lesions appear on leaves and will expand rapidly under conditions of warm temperatures (greater than 75 degrees) and high humidity.