Table Of Content

Wheat Disease Identification Contents Diseases affecting heads and grain Common bunt .........................................................................1 Fusarium head blight ...............................................................2 Loose smut ..............................................................................3 Sooty head molds .....................................................................4 Stagonospora nodorum blotch .................................................5 Diseases affecting leaves Bacterial streak ........................................................................6 Barley yellow dwarf ..................................................................7 Leaf rust ..................................................................................8 Powdery mildew ......................................................................9 Septoria tritici blotch ..............................................................10 Stagonospora nodorum blotch ................................................11 Stem rust ...............................................................................12 Stripe rust .............................................................................13 Tan spot .................................................................................14 Wheat soilborne mosaic .........................................................15 Wheat spindle streak mosaic ...................................................16 Wheat streak mosaic ...............................................................17 Diseases affecting stem and roots Cephalosporium stripe ...........................................................18 Common root rot ....................................................................19 Fusarium root, crown, and foot rots .......................................20 Take-all................................................................................. 21 Common bunt D i Wheat kernels infected by common bunt have a gray- s green color and are wider than healthy kernels. Diseased e kernels can be seen in developing wheat heads but are a s often not detected until harvest. The outer layers of e diseased kernels remain intact initially but are easily s broken during grain harvest, releasing masses of black, a powdery spores. The fungus produces chemicals with f a fishy odor, which sometimes causes this disease to be f e referred to as “stinking smut.” c Management: Fungicide seed treatment, disease-free t i seed sources. n g h e a d s a n d g r a i n 1 n Fusarium head blight i a Symptoms of Fusarium head blight include tan or light r brown lesions encompassing one or more spikelets. Some g diseased spikelets may have a dark brown discoloration d at the base and an orange fungal mass along the lower n portion of the glume. Grain from plants infected by a Fusarium head blight is often shriveled and has a white s chalky appearance. Some kernels may have a pink d discoloration. a Management: Avoid the most susceptible varieties and e planting into corn residue, foliar fungicides. h g n i t c e f f a s e s a e s i D 2 Loose smut D i The normal head tissue of plants infected by loose smut s is completely replaced with dark masses of fungal spores, e giving the heads a black powdery appearance. It is a s possible to see heads damaged by loose smut while much e of the head is still inside the boot. Only the central stem s of the head is left after the spores are released. a Management: Fungicide seed treatment, disease-free f f seed sources. e c t i n g h e a d s a n d g r a i n 3 n Sooty head molds i a Sooty head molds are characterized by a dark green or r black mold growth on the surface of mature wheat heads. g These molds are part of a naturally occurring complex d of organisms that help to decay dead plant debris. Sooty n molds are most common when mature wheat is subjected a to repeated rains and delayed harvest. This disease also s may affect plants that have been damaged by root rot. d The sooty head mold growth is normally superficial. Its a affect on grain is thought to be minor, but it can make e for dusty harvest operations. Sooty molds can contribute h to a discoloration of the grain called “black point.” g Management: Generally impractical or not needed. n i t c e f f a s e s a e s i D 4 Stagonospora nodorum blotch D i This disease causes dark brown or purple lesions on s heads. Lesions are often more intense at the top of the e glume, with brown streaks or blotches extending down a s toward the base of the spikelet. The presence of tiny e fungal reproductive structures embedded in the tissue s can confirm the diagnosis but will require significant a magnification. f f Management: Genetic resistance, foliar fungicides, crop e rotation, fungicide seed treatment. c t i n g h e a d s a n d g r a i n 5 s Bacterial streak e v Early symptoms of bacterial streak include small, water- a soaked areas between leaf veins. These water-soaked e areas become tan streaks within a few days. When l the disease is severe, streaks may merge to form large, g irregular areas of dead tissue. When dew is present, the n bacteria causing this disease may ooze from the lesions i t and dry to form a clear, thin film. This film flakes easily c and is visible when the leaf is viewed from different e perspectives. f f a Management: Avoid highly susceptible varieties. e s a e s i D 6 Barley yellow dwarf D i This viral disease causes wheat leaves to have a yellow or s red discoloration. The discoloration is often more intense e near the tip of affected leaves, giving them a flame-like a s appearance. Barley yellow dwarf often occurs in patches e within a field. The size and distribution of these patches a depends on the feeding activity of aphids, which spread f barley yellow dwarf virus. Infected plants within these f e patches may be shorter than neighboring healthy plants. c Management: Genetic resistance, delayed planting date, t i insecticide seed treatment. n g l e a v e s 7 s Leaf rust e v Small, orangish-brown lesions are key features of leaf a rust infections. These blister-like lesions are most e common on leaves but can occur on the leaf sheath, l which extends from the base of the leaf blade to the stem g node. Lesions caused by leaf rust are normally smaller, n more round, and cause less tearing of the leaf tissue than i t those caused by stem rust. c e Management: Genetic resistance, foliar fungicides. f f a e s a e s i D 8