Barley Basal Glume Blotch Info
What is basal glume blotch of barley? Also known as barley basal glume rot and spikelet rot, this disease is caused by the bacterium Pseudomonas atrofaciens (sometimes also called Pseudomonas syringae pv. atrofaciens), which is the same fungus that can also lead to septoria leaf blotch. It affects the glume of the plant, or the small bract that grows out of the stem partially covering each kernel of grain. Symptoms of glume blotch begin with small, dark green, watery lesions appearing on the base of the glumes that may turn whitish-gray. Eventually, during the stages of disease development these lesions will change to a dark brown or near black discoloration, and may spread across the entire diseased glume. If held up to the light, the infected glumes appear translucent. A gray ooze might develop on the base of the glumes, and dark water-soaked spots may appear on the leaves. If young seedlings are infected with the disease, they may be overtaken by these watery lesions and die.
How it Spreads
Barley basal glume blotch disease is spread by dust blown in the wind, and often transfers from crop residue. It can also be delivered by rain splash and carried by insects. The bacteria can live on the surface of barley plants until it has the ideal conditions for infecting them.
Managing Basal Glume Blotch Disease
Barley basal glume rot is primarily borne by seed, which means the best way to hold off the disease is to plant barley seed that is treated with fungicide prior to planting. Seed treatments, while helpful, won’t protect the plants from spores from crop residue, so be sure to plow under any crop residue into the soil. Practicing crop rotation helps to reduce the buildup of this disease in the soil and will help knock back the numbers of any bacteria present in the soil. Crop rotation will also reduce the likelihood of other diseases damaging the seed and giving the blotch bacteria a pathway in. The best practice is to allow one or two years between barley and wheat crops. The bacteria can survive in the soil and on the surface of the plant as well, and spreads best in warm, damp conditions. You can help prevent this spread by only irrigating from below and spacing plants out to encourage good airflow. Glume rot on barley doesn’t have to spell doom for a barley crop, but prevention is key to growing this crop effectively.
