Most smal1 grains and many grasses are affected, but wheat is
the only important commercial host.
Symptoms and Signs
Septoria leaf spot first appears as small, light green to yellow
spots between veins of the lower leaves. The spots elongate to
form light brown to reddish brown, irregular lesions. Scattered,
small, dark brown to black pycnidia, easily seen with a hand
lens, are embedded in lesions, which sometimes have ashen centers.
Glume blotch develops mainly in areas where the weather is
warm and moist. It appears as small, irregular gray to brown
spots or blotches on the glumes, although infections may also
occur at the nodes. When the lesions enlarge, a sprinkling of
The fungi survive on seed, straw or stubble. Conidia can remain
viable for several months between 34 and 50F in the slime in
which they are exuded. S. nodorum tolerates even warmer
temperatures. At least 6 hours of wetness and temperatures between
41 and 95F are needed for infection. Prolonged wet, windy weather
favors Septoria diseases.
Ascospores or conidia germinate to infect directly through
the epidermis or through stomata. Eventually pycnidia develop.
Secondary disease cycles occur as long as weather conditions
are favorable and host tissue is available.
Chemical. Protective foliar sprays are used
in areas where losses are severe. Seed treatments with appropriate
fungicides can also reduce disease severity.
Cultural. Plant Septoria free seed. Early
seeding of winter wheat promotes good growth in the fall and
increases both the over-wintering vigor of the plants and their
ability to withstand damage. Rotating crops out of cereals and
grasses for 3-4 years, deep plowing wheat stubble, and destroying
volunteer hosts reduce the amount of inoculum. Minimum tillage
practices may increase disease risk. Septoria diseases are especially
prevalent when wheat has dense foliage and is heavily fertilized.
Eyal, Z., A.L. Scharen, J.M. Prescott, and M. van Ginkel. 1987.
The septoria diseases of wheat: Concepts and methods of disease
management. Mexico, D.F. CIMMYT.
Luke, H.H., R.D. Barnett, and P.L. Pfahler. 1986. Development
of Septoria nodorum blotch on wheat from infected and
treated seed. Plant Disease 70:252-254.
Other Interesting Septoria
Agriculture, Food and Rural Development -- description and
of Nebraska NebGuide -- description and pictures.
Diseases * Barley
Home Page * Small
Grains Home * Grow Serve
Edited and reviewed by Ed Adams, WSU Extension Plant Pathologist
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