Wheat and Durum

Stem and Leaf Diseases – Fungal

STEM RUST, Puccinia graminis tritici

Symptoms. Typical symptoms are elongated, brick red pustules (eruptions) on the leaf blade, sheath, and stem. Pustules turn black late in the season. Pustules may also appear on glumes. Seed has low test weight and poor emergence. Severe yield loss may occur.
Survival and Spread. Red spores can be carried great distances by the wind. Spores are carried by wind into North Dakota from wheat growing areas to the south; infection may repeat every eight to 14 days.
Other Crops Affected. Barley and wild grasses.
Control. Most recommended hard red spring wheats and durums grown in North Dakota are resistant to existing races. Winter wheats vary in resistance. Check the current variety recommendations for variety susceptibility. Eradicate common barberry, the alternate host of stem rust. Since the federal eradication program was abandoned, barberry is gradually moving back into the upper Midwest.
Remarks. New races may form on common barberry (not Japanese barberry), and mutations may occur.

LEAF RUST, Puccinia recondita

Symptoms. Circular to oblong orange-colored pustules occur primarily on leaves. Later in the season the pustules are black and usually do not break through the epidermis. Seed test weight and yield are reduced.
Survival and Spread. Orange spores are spread from plant to plant by the wind; usually they blow in from major winter wheat states in the southern plains. Temperatures of 60-80�F and dew periods of six to eight hours favor infection.
Control. Use resistant varieties. Check the current variety information for susceptibility of available varieties. Fungicide control: spray mancozeb at early boot and 10 days later to protect the flag leaf, or spray a single application of triadimefon at early boot, or propiconazole when flag leaf is emerging (Feeke's growth stage 8).
Remarks. New races may occur by mutations.

POWDERY MILDEW, Erysiphe graminis tritici

Symptoms. A white to grey, powdery superficial growth occurs on leaves, stems and sometimes heads. Black pin-head size dots may develop (fungus fruiting bodies). Eventually, yellowing, browning and drying out of leaf tissue occurs. If severe, yields are reduced.
Survival and Spread. Spores are windblown from residue. The disease is favored by cool, humid conditions.
Control. Crop rotation and destruction of host residues through tillage reduce disease risk. Chemical control: spray sulfur or triadimefon fungicide at early boot to protect the flag leaf or spray propiconazole when flag leaf is emerging (Feeke's growth stage 8).

SEPTORIA LEAF BLOTCH, Stagonospora nodorum, (= Septoria nodorum) Stagonospora (Septoria) avenae f. sp. triticea, and Septoria tritici

Symptoms. Leaves develop straw-colored spots that later form grayish-white centers. Very tiny black fruiting bodies (specks) may develop in the spots. Severely diseased plants have "fired" leaves, yield loss, and shriveled seed. Stagono-spora nodorum also infects the glumes (see Glume Blotch).
Survival and Spread. Survives on infected straw and stubble and on seed. Spread by airborne spores and splashing rain.
Other Crops Affected. Barley
Control. Differences in variety response exist: Check current variety information for susceptibilities to leaf spot fungi. Use fungicidal seed treatment to control seed-borne infection. Fungicide sprays are available. Benomyl, copper hydroxide, mancozeb, triadimefon, and propiconazole are registered for Septoria control, with some fungicides requiring tank mix partners for adequate control. Use crop rotation or bury crop refuse with tillage. Clean seed severely and discard shriveled kernels.
Remarks. Infection by all three fungi is favored by wet weather and relatively warm temperatures (60-70�F for S. avenae f. sp.triticea and S. tritici and 70-80�F for S. nodorum).

SPOT BLOTCH, Cochliobolus sativus (= Helminthosporium sativum)

See description under barley.

TAN SPOT, Pyrenophora tritici-repentis

Symptoms. Elliptic or diamond shaped tan spots form on leaves, often with a yellow border and a small chocolate brown center. Severe disease causes "firing" of leaves, yield loss, and low test weight seed.
Survival and Spread. Survives on infected straw and stubble, on wild grasses, and rarely on seed. Spores are airborne and also spread by splashing rain. Long periods (24-48 hours) of moisture on the wheat leaves favor infection of modern cultivars.
Other Crops Affected. Bromegrass, rye and wheat grass.
Control. Varieties vary in susceptibility. Check variety information publications for susceptibility to leaf spot fungi. Crop rotations or burying crop refuse by tillage reduces early infection but may not prevent late infection. Later applications may be directed to the flag leaf; propiconazole must be sprayed at early flag leaf emergence ( Feeke's growth stage 8.) Early applications of mancozeb or propiconazole fungicides may protect the tillers from early infections. Both fungicides have good activity against leaf spots on wheat.
Remarks. Late in season large numbers of spores may be blown considerable distances.

Stem and Leaf Diseases – Bacterial

BACTERIAL BLIGHT, Xanthomonas translucens pv. translucens (= X. campestris pv. translucens)

Symptoms. Water-soaked dark green stripes develop on leaves, turning yellow and finally dark brown; a yellow exudate forms in wet weather. Also infects heads (see Black Chaff). Early infection causes dwarfed heads and shriveled seed.
Survival and Spread. Survives on infected seed, straw and winter grass hosts. Spread by splashing rain, aerosols, and insects.
Other Crops Affected. Barley and rye.
Control. No satisfactory control; crop rotation and burying infected stubble is of limited value. Avoid seed from infected fields. Not controlled by foliar fungicides.

BACTERIAL LEAF BLIGHT, Pseudomonas syringae pv. syringae

Symptoms. Develops on uppermost leaves after plant reaches boot stage. Initial tiny, water-soaked spots expand and become necrotic and turn from gray-green to tan-white. Entire leaves may become necrotic. During very wet periods, white droplets of bacteria may be visible.
Survival and Spread. Survives in soil and water. Spreads by wind-driven rain and enters plants through wounds or natural openings.
Other Crops Affected. Barley and rye.
Control. None recommended.

Stem and Leaf Diseases – Virus

BARLEY YELLOW DWARF, Barley Yellow Dwarf Virus

See description under barley

WHEAT STREAK MOSAIC, Wheat Streak Mosaic Virus

Symptoms. Leaves develop intermittent yellow and green stripes or streaks. Severely diseased leaves turn brown and die. Plants are stunted. Yield is poor and seed has a low test weight.
Survival and Spread. Survives in infected winter wheat, volunteer wheat, and several native grasses. Spread by the wheat curl mite (Aceria tulipae), which is wind-borne.
Other Crops Affected. Barley, corn, oats, rye, and some grasses and volunteer wheat.
Control. Plant winter wheat around mid-September and plant spring wheat early. Destroy volunteer wheat and grasses two weeks before planting winter wheat. Avoid planting winter wheat next to corn and spring wheat next to volunteer winter wheat. Do not overseed damaged winter wheat stands with spring wheat. Check winter wheat variety trial information for differences in susceptibility to wheat streak mosaic.
Remarks. A problem in the winter wheat areas of North Dakota.

Stem and Leaf Diseases – Non-Infectious

HEAT CANKER, Non-Infectious

Symptoms. Seedling stems may be constricted at the soil line; the seedling may fall over. In less severe cases several white bands may appear on one or more leaves; these bands go across the leaf. May be common in a hot, dry spring.
Survival and Spread. Non-infectious. Favored by dark soils and hot sunny days before plants are large enough to shade the soil -- plant tissues at the soil line are injured by hot soil. Mild injury causes white bands; each one corresponds to high soil temperatures when that portion of the leaf was in the whorl at soil line. Severe injury causes a stem constriction.
Control. Early planting, drilling rows north and south for maximum shading and using higher seeding rates may reduce the damage.

Head and Seed Diseases – Fungal

BLACK POINT, Cochliobolus sativus (= Helminthosporium sativum) and related fungi

Symptoms. In wet weather, developing seeds in the head are infected by Helminthosporium or Alternaria, resulting in shriveled blackened kernels. The blackened area is often near the embryo or germ end, hence the name black point. The crease also may be blackened. Planting of black-pointed kernels may result in seedling blight. Seedlings turn yellow, roots are blackened and plants die or are stunted.
Survival and Spread. Survives in soil, crop refuse, and on and in black-pointed seed. Spread by wind and splashing rain.
Other Crops Affected. Barley and grasses.
Control. Use fungicidal seed treatment to reduce seedling blight. Use crop rotation. Clean and condition black-pointed seed and discard shriveled seed. Bury crop refuse by tillage to reduce chance of fungal spores splashing to the head.

ERGOT, Claviceps purpurea

See description under rye.

GLUME BLOTCH, Stagonospora nodorum (= Septoria nodorum)

Symptoms. Tips of glumes have either a bleached to greyish appearance or a brownish discoloration. Infected awns exhibit brown spotting. Small fruiting bodies may be evident in glume tips. Grain is very shriveled.
Survival and Spread. Survives on infected straw and stubble and on seed. Spread by airborne spores and splashing rain.
Other Crops Affected. Barley.
Control. Check variety recommendations for susceptibility to fungal leaf spots. Use fungicidal seed treatment to control seed-borne infection. Clean seed severely and discard shriveled kernels. Tillage to bury stubble and rotations away from wheat minimizes carryover of the disease organism. Foliar fungicides may reduce Septoria leaf blotch, but their activity may not last sufficiently long to protect against glume blotch.

LOOSE SMUT, Ustilago tritici

Symptoms. The fungus grows internally, along with the growing point, following germination of the infected seed. No symptoms appear until heading. Affected heads may emerge earlier than healthy ones and are a powdery mass of black smut spores that replace grain and chaff. No smut balls form.
Survival and Spread. Flowers are infected at blossom time by wind-borne spores from smutted heads. Seed (embryo) is invaded and cannot be distinguished from healthy seed.
Other Crops Affected. Some grasses, but not barley or oats. Loose smuts on barley and oats are caused by similar fungi, but not by the same fungus that causes wheat loose smut.
Control. Several seed treatment fungicides, those containing carboxin, difenoconazole, or triadimenol, will control loose smut.

SCAB (HEAD BLIGHT), Fusarium sp. (Gibberella zeae)

Symptoms. All or any part of the head may blight any time from flowering to maturity; affected parts turn white, or may be salmon colored from the spores, in wet weather. Seeds are light and shriveled, frequently grayish or pinkish "tombstones." Yields and test weights are reduced. Seedlings grown from infected seeds turn yellow and die or re-root at soil line.
Survival and Spread. Spores airborne for considerable distance. Fungus also soil-borne. Carried on and in infected seed. Survives in infected seed and crop refuse; survives very well in corn crop refuse.
Other Crops Affected. Barley, corn, grasses, oats and rye.
Control. Differences in susceptibility to scab exist among varieties. Check variety information for a variety's response to scab. Severely clean to remove badly infected seed. Use fungicidal seed treatment to prevent seedling blight. Use tillage to bury crop refuse and use crop rotations. Avoid planting small grains on corn land. Benomyl fungicide is registered (1996) for wheat for suppression of the head infection of scab; other fungicides may also have some ability to suppress scab.
Remarks. Scabby grain may contain a mycotoxin and can cause vomiting and feed refusal in nonruminant livestock.

STINKING SMUT (BUNT), Tilletia foetida, Tilletia caries

Symptoms. Infection occurs during seedling development but no symptoms show until heading. Heads on infected plants may be partly or entirely affected. Smut balls replace seeds. Smut balls are enclosed with gray membranes that break at harvest releasing black spores.
Survival and Spread. Survives as bunt balls and spores. Balls break at harvest and black spores cover healthy seeds. Spores can live eight years or more. May also survive in the soil. Spread by wind.
Other Crops Affected. Rye and wild grasses.
Control. Use protectant fungicide seed treatment.
Remarks. Smutted wheat has a fishy odor, not suited for milling unless scoured -- price discounted at elevator. Not currently (1996) found in North Dakota but present in many other plains states. Could be introduced from out-of-state seed or from contaminated equipment.

Head and Seed Diseases – Bacterial

BASAL GLUME ROT, Pseudomonas syringae pv. atrofaciens

Symptoms. Dark brownish-black streaks on the glumes, mostly on the lower half. Germ end of the seed varies from faint brown to charcoal black and seed may be severely shrunken.
Survival and Spread. Survives in infected seed and in soil. Spread by wind and insects.
Control. Use clean seed.
Remarks. Fairly common in North Dakota, but usually not highly significant.

BLACK CHAFF, Xanthomonas translucens pv. translucens

Symptoms. Stem at base of head develops thin black stripes. Black stripes form on glumes and alternating dark and light spots develop on awns ("barber pole" effect). Blighted seedlings develop when infected seed is planted.
Survival and Spread. Survives on infected seed and straw. Spread by splashing rain, aerosols, and insects.
Other Crops Affected. Barley and rye. Rarely attacks oats.
Control. No satisfactory control; crop rotation and burying infected stubble is of limited value. Avoid seed from infected fields. Not controlled by foliar fungicides.

BACTERIAL PINK SEED, Erwinia rhapontici

Symptoms. Kernels appear pink but maintain plumpness and vitreousness. More easily seen in durum.
Survival and Spread. Survives on crop residue. Generally invades kernels harvested prematurely or grain in the swath.
Control. Occurs infrequently. No control measures prescribed.

Root Diseases – Fungal

COMMON ROOT ROT, Cochliobolus sativus(= Helminthosporium sativum)

Symptoms. Subcrown internode (portion connecting seed to crown), roots and crown tissue are dark brown or with dark brown lesions. Spikelets on affected plants are frequently empty and heads and whole plants are prematurely ripened or bleached.
Survival and Spread. Survives as spores and vegetative strands in soil and on crop refuse.
Other Crops Affected. Barley and grasses.
Control. Crop rotation. Use more tolerant varieties. Differences among varieties are listed in the North Dakota variety description circulars. Seed treatment fungicides, imazalil, difenoconazole, and triadimenol are available for suppression of common root rot.

SNOW ROT AND SNOW MOLD, Pythium and Fusarium spp.

Symptoms. Irregular patches to scattered plants turn brown to bleached in appearance. Roots and crown are decayed.
Survival and Spread. Survives in soil as spores, sclerotia and vegetative growth. Most severe in winter wheat following heavy snow cover, or following frequent snows or rains early in spring.
Other Crops Affected. Winter cereals, lawn grasses.
Control. Avoid planting in areas of frequent, dense snow cover. Rotation helps reduce inoculum levels.

TAKE-ALL, Gaeumannomyces graminis tritici

Symptoms. Roots, crown and lower stem are distinctly blackened, often shiny black. Roots may be brittle. Prematurely whitened heads and stunted plants also are typical.
Survival and Spread. Survives in soil and host debris. Infection favored by high soil moisture and high soil alkalinity. Most frequently found on irrigated ground but also in dryland crops in excessively wet years.
Other Crops Affected. Barley, rye, wheat, grasses.
Control. Crop rotation to non-susceptible host. Avoid excessive irrigation. Use of ammonium nitrogen, not nitrate nitrogen forms, may reduce the risk of take-all. Seed treatment products difenoconazole and triadimenol are available for suppression of take-all.