Plant Disease Management Handbook

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Greenhouse Plants, Ornamental - Impatiens Necrotic Spot

Symptoms Brown lines occur in concentric patterns around or near the petiole.

Close up of African Violet flower with western flower thrips in the lower left corner.

Stacey Fisher, 1991.

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Greenhouse Plants, Ornamental - Gray Mold

Cause Botrytis cinerea, a fungus. The disease may become severe when plants are crowded and growing conditions are humid. This fungus readily colonizes senescent leaves and flower parts.

Image related to African Violet (Saintpaulia spp.)-Gray Mold

Infected flowers become water soaked, droop and may develop the fuzzy growth of the fungal spores.

Jay W. Pscheidt, 2013.

Petioles can also become infected and show the gray sporulation of the fungus.

Jay W. Pscheidt, 2013.

Gray sporulation of Botrytis under moist conditions.

Jay W. Pscheidt, 2013.

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Maple (Acer spp.)

These are only two of the many different types of Acer spp. (maples) that can be found in nurseries and nature.

Jay W. Pscheidt.

Cause What looks like a normal genetic variegation is due to the abutilon mosaic bigeminivirus (AbMV). These phloem-limited viruses are composed of single-stranded DNA and replicate best in young leaves. A single variegated seedling was imported into England from the West Indies in 1868 and vegetatively propagated as an ornamental cultivar. Although transmission occurs through grafting, it is naturally transmitted by a whitefly (Bemisia tabaci) in Brazil.