Glume blotch (Septoria nodorum (alternative name Phaeosphaeria nodorum))

Glume blotch: biology

Overwinters on crop residue and produces two spore stages. One of these is short distance, rain-splash dispersed and the other long distance, wind dispersed. Wet warm weather favors the disease. The same fungus also causes septoria leaf blotch. The disease is also seed-borne but inoculum from seed is usually minor relative to inoculum from crop residue.

Glume blotch: damage description

Glume blotch

Purplish-brown to grey lesions develop on a few or many glumes of infected heads. Small black dots, the sporulating structures of the fungus which causes glume blotch may appear in the diseased areas.

Septoria leaf blotch and glume blotch cause shrivelled seed which reduces yield. Seed set can also be reduced.

Glume blotch: management

Allow one and preferably two years between wheat and/or barley crops. Burying crop residue may help to reduce disease incidence. Applying a fungicide to control the foliar phase of this disease, septoria leaf blotch, will usually reduce glume blotch. Seed treatments will reduce seed transmission but will not protect plants from spores spreading from crop residue, typically where the disease originates.