Control Plant Disease
For Better Farming and Better Living

Mimeo BP 1-11
January 1958

Chrysanthemum Diseases
A favorite name for a baby girl in Japan is O-Kiku-San which means "Hon-
orable Miss Chrysanthemum". To the Japanese, the chrysanthemum, the nation-
al flower, means perfection, and because the blooms last so long it is a
symbol of long life, A gracious custom of the Japanese is to hand a guest a
cup of wine on which are floating chrysanthemum petals since this conveys a
wish for health and long days on earth. Our word "chrysanthemum" is derived
from the two Greek words meaning "Gold Flower" because all of the early vari-
eties were yellow. Chrysanthemums were introduced into America almost a
century ago and most of our modern "mums" have been developed by crossing or
selection of native Chinese or Japanese ancestors. The hardy chrysanthemum
is a popular perennial dweller in many Hoosier home gardens.
There are several diseases of garden "mums" that may become destructive
and cause concern to the home owners. The diseases described below are the
most frequent problems in Hoosier gardens although there are a number of
other diseases that occasionally may be destructive,

Fusarium Wilt and Stem Rot
This disease is caused by the soil borne fungus Fusarium sp. Mums in-
fected with this disease will first exhibit a yellowing of the lower leaves
which is quickly followed by a wilting and ultimate death of the entire plant.
The lower portion of stems of plants infected with this trouble usually turns
black on the surface and when examined in cross section will show a discolora-
tion of the internal woody tissue. Once the disease becomes established in
the garden nothing can be prescribed for its cure. All diseased plants should
be removed and destroyed as soon as they appear and a new bed should be es-
tablished in a new location using disease-free plants.

Yellows
Frequently mums will produce sickly green flowers, or part of the flower
will be normal in color and the remaining portion green. This is caused by a
virus disease known as "yellows". Infected plants may produce both normal-
colored and green-colored blossoms. The leaves of infected plants are usually
slightly yellow with burned or scorched edges. Virus infected mums never pro-
duce normal seed. Virus diseases such as chrysanthemum yellows cannot be
cured once they are present in the garden. The only effective control is to
inspect carefully the garden when the plants are in bloom removing and destroy-
ing all plants showing symptoms of the disease. Cuttings for propagation
should be taken only from healthy plants and control of insects such as aphids,
thrips and leaf hoppers is important in preventing spread of chrysanthemum
yellows (refer to Purdue mimeograph E-70 Insect Pests of the Flower Garden).

Powdery Mildew
In wet years powdery mildew is also certain to occur on chrysanthemums
in most home gardens, Frequently mildew will not appear until late fall when

PURDUE UNIVERSITY Agricultural Extension Service, Lafayette, Indiana
Department of Botany and Plant Pathology, Life Science Building