Michigan State University Extension
Ornamental Plants plus Version 3.0 - 00000671
11/12/99
GLADIOLUS DISEASE PROBLEMS
Bacterial blight is serious in wet weather or on plants
grown in poorly drained soil. Infected areas are first
irregular, water-soaked spots that later dry out and turn
brown. The whole leaf becomes involved and dies. A slimy
exudate may be seen. Discard infected corms.
Scab causes pale yellow, water-soaked lesions on the
corms. The lesions turn brown or nearly black, become
sunken and have a raised brittle margin. The lesions
exude a gummy substance. Early symptoms on the leaves are
raised reddish specks near the leaf bases. The neck of
the plant rots and the plant falls over. Discard infected
corms.
Corm rot causes corky decay with sunken, reddish brown
lesions. At low temperatures the lesions are covered with
green mold. The disease originates where husks are
attached to the corm. Avoid wounding corms and store them
in a cool dry cellar at 35 to 45 degrees to prevent
initial infections. Prompt curing and drying of corms is
essential. Cure newly dug corms at 85 degrees for 10 to
15 days. This disease is caused by Penicillium gladioli.
Hard rot is a storage problem. The corms are mummified.
Brown to purplish brown lesions form on the leaves. The
lower part of the corm is most severely attacked. Discard
infected corms.
Dry rot causes circular, sunken spots on the corms. Brown
or black lesions on the corms run together and destroy the
whole corm, especially in moist storage rooms. The husks
or leaf bases of infected plants are discolored and
brittle. Leaves from infected corms turn yellow and
decay. Use a new planting area and discard infected
corms. This problem is caused by Stromatinia gladioli.
Botrytis dry rot causes corm rot and leaf and flower spot.
The stems rot at the soil line or just below it. Plant
where the soil and air drainage is good. Destroy diseased
plants.
Wilt causes leaves of infected plants to yellow and the
stems to collapse. Mildly infected corms may not show
symptoms when dug but may rot in storage. The disease is
caused by Fusarium orthoceras.
Smut causes blistering, shredding and dying of stem and
leaf tissue.
Leaf and flower spot causes oval, tan to dark brown spots
on the leaves and stems. Florets on heavily infected
plants do not open. The disease is caused by Curvularia
trifolii.
Several virus cause color breaks in the flowers. There is
no chemical control.
Related information.
Pesticide Recommendations
Fungal and Bacterial Leaf Diseases
This information is for educational purposes only. References
to commercial products or trade names does not imply
endorsement by MSU Extension or bias against those not
mentioned. This information becomes public property upon
publication and may be printed verbatim with credit to MSU
Extension. Reprinting cannot be used to endorse or advertise
a commercial product or company.
This file was generated from data base ZZ on 01/19/00.
Data base ZZ was last revised on 11/12/99.
For more information about this data base or its contents please contact
heatley@msue.msu.edu . Please read our
disclaimer for important
information about using our site.