Barley loose smut is a disease that infects barley during the flowering stages of development. This disease is seed transmitted and can cause significant yield losses in the field. Today, the use of fungicides and resistant cultivars has resulted in loose smut becoming less prevalent and damaging than in the past. It is important to note that this disease is present during every growing season to various degrees and has the potential to cause yield loss if control measures are not followed. Wet growing seasons or wet areas may have higher levels of seed infection than dryer areas or dry years.
Barley loose smut is a fungal disease caused by the organism Ustilago nuda. Loose smut only survives to the next growing season as dormant mycelium inside barley seed embryos. Once infected seed are planted, the fungus begins to grow and infects head tissue. The infected head becomes a source of spores to infect other plants during flowering.
The Seed Department requires all certified barley seed in North Dakota to be tested for loose smut. There are no set limits on seed infection levels, however, at levels of 2% seed infection or higher, the department recommends that the grower apply a seed treatment.
The Seed Department currently tests for loose smut in barley. The embryo count method is used where the number of infected embryos in 500 seed are determined. Results of this test are reported as percent infected seed of 500 seed tested. This test is typically completed in two to three days.