Cause The soilborne fungus, Cephalosporium gramineum (sexual: Hymenula cerealis), overwinters in association with infected crop residue. Plants are infected through wounds in the root system caused by cultivation (including fertilizer application), frost heaving, freeze damage without heaving, or soil insects. Because frost heaving aggravates disease development, the disease is worse on wet, poorly drained soils.
Note the necrotic areas on the stems.
Photo by Paul Koepsell, 1973.
Cause Numerous species of fungi, including Alternaria alternata, Fusarium spp. including F. oxysporum, and Helminthosporium spp. Fusarium proliferatum is one species that has been reported to pathogenic to wheat if it occurs on seed.
Note the infected Stephens wheat plant on the left and a normal plant on the right.
Photo part of OSU Extension Plant Pathology Slide Collection
Leaf tips of affected wheat in May.
Photo by Cynthia M. Ocamb, 2009.
Leaf tips of affected wheat in June.
Photo by Cynthia M. Ocamb, 2009.
Cause The bacterium, Xanthomonas translucens pv. undulosa (formerly X. campestris pv. translucens), infects many cereals (barley, oats, rye, triticale) and grasses. Severe epidemics are periodic in irrigated wheat. The pathogen may be seedborne or persist in soil and infected plant residue. The disease can spread by water, spike-visiting insects (aphids), plant-to-plant contact, and seeds.
Symptoms on stems of Triticum durum 'Waid'.
Bob Forster collection
Slimy droplets may develop on diseased tissue in wet weather.
Bob Forster collection
Symptoms in heads consist of dark-brown, black, or purple streaks and blotches.
Bob Forster collection
Diseased heads may be sterile if infected before flowering. Triticum durum 'Waid'.
Bob Forster collection
Cause The bacterium, Pseudomonas syringae pv. syringae, causes a disease favored by cool to mild temperatures (59°F to 77°F) and high relative humidity. The bacterium is in seeds, soil, plant residues, and water and may spread by infected seed or water. Severe epidemics are periodic in irrigated wheat. Other cereals may be affected, including oats, rye, and triticale.
