Gail Ruhl, Senior Plant Disease Diagnostician,
Director, Botany & Plant Pathology
Powdery mildew is the name for the grayish white powdery coating
of fungus mycelium and masses of spores growing on plant leaves,
shoots and flowers. This disease is caused by a distinct group
of similar fungi that attacks a wide variety of plants. Here
it is seen infecting an ornamental honeysuckle.
Although plants infected with powdery mildew rarely die, the
disease can diminish the beauty of landscape ornamentals.
Conditions including high humidity, overcast weather, warm days
and cool nights favor powdery mildew development. The disease
is common in crowded plantings and in areas with restricted air
movement, thus to reduce infection, cultural control recommendations
include adequate spacing between plants and in the landscape,
choosing the right plant for the right location so as to make
conditions less favorable for the disease.
There is no cure for infected plants, however preventative fungicide
sprays will help protect healthy plant tissue from infection.
Products containing active ingredients such as chlorothalonil,
triademefon, triforine, and sulfur are labeled for control of
powdery mildew. Hosts and diseases listed on specific product
labels may differ between products containing the same active
ingredient, thus be sure to read the label.
At the end of the growing season, destroy or discard powdery
mildew-infected annuals and leaves of shrubs to reduce carryover
of the mildew fungi into the next season.
Lonicera x brownii
As per Mary Welch-Keesey, Purdue University Consumer Horticulture Specialist
at White River Gardens, this is NOT an invasive honeysuckle. One of the parents
is L. sempervivens, our native trumpet honeysuckle. Beloved of hummingbirds,