wheat pest and diseases

Hosts/Distribution: Root knot nematodes have a very wide host range, including all small grain cereals. Disease symptoms. The degree of disease establishment and development depends on environmental conditions from spike emergence through grain filling. The application of such hormonal herbicides as 2,4-D too early in the crop cycle can cause leaf curling and deformed spikes (104); application near anthesis can cause sterility. Yield losses of from 14% to more than 25% have occurred with natural infestations. Curling and rolling of leaves during midday also are symptoms of moisture stress (102). Under wet or humid conditions, a whitish gray bacterial ooze may be present. Development: Spores are produced on crop debris left on or near the soil surface. Importance: Considerable yield losses can occur when susceptible cultivars are grown or chemical seed treatments are not used. Development: The pathogens survives on crop debris, as well as various grass hosts. These pathogens invade the vascular system or intercellular spaces in host tissue, and necrosis results from toxins produced or enzymatic activity of the bacteria. The infectious viral particle is called a virion, which is a stable, non-multiplying stage by which the virus is transferred from one plant to another. Barley yellow dwarf virus Leaf and Head Diseases When the disease is severe, affected leaves or leaf sheaths may die prematurely. Experience and knowledge in identifying and treating these diseases are crucial because if misdiagnosed or improperly treated the problem can be worsened. The size of grain kernel and ergot are similar in size. White spikes often are visible just prior to normal physiological maturity (42). Green portions of the leaves may be bluish-green and the base of the culms purple. Viruses are the smallest pathogens presented in this field guide, and only one viral disease (BYD) is discussed. Symptoms: When no pathogen can be identified as the cause of leaf spotting (89), the symptom may be caused by a physiological disorder or a mineral deficiency (for example, manganese deficiency). Damage can be severe in some years, but the insect seldom causes widespread damage. However, lady beetles such as Coccinella and Hippodamia are too large to enter the rolled leaves in which Russian wheat … Symptoms: Salt concentrations within a field are rarely uniform; therefore, one of the first symptome indicating a salt problem is variability in crop growth within the field (barren spots are not uncommon) (101). Glume blotch Septoria nodorum. Life Cycle: Wireworms are the larvae of click beetles, of which there are many species. Life Cycle: White grubs are the larvae of May or June beetles. Sclerotia require cold temperatures before they can germinate. are present in nearly all soils and crop residues. This bacteria is associated with the nematode Anguina tritici in some regions. Wheats with hairy leaves are affected less. Hosts/Distribution: The disease can affect all small grain cereal crops; distribution is worldwide. Eventually, black spherical fruiting structures (cleistothecia) may develop in the mycelia, and can be seen without magnification. Check the seeds for ripeness before harvest. Hosts/Distribution: Species commonly found on cereals throughout the world include: Importance: Aphids are important and widespread pests on cereal crops. All photographs compliments of CIMMYT staff, except for photo 57, contributed by C. C. Gill, Agriculture Canada, Winnipeg, Manitoba, Canada, and photo 70, contributed by J. H. Hatchett, USDA-ARS, Kansas State University, Manhattan, Kansas, USA. The alternate hosts are Thalictrum, Isopryum, Anemonella, and Anchusa spp. Life Cycle: The insect produces one generation per year. Dr. Anders Huseth, NC State Extension Specialist in Field Crops will be discussing “Wheat Insect Pest Management”. By Aditya Abhishek December 7, 2020 December 7, 2020 Aditya Abhishek December 7, 2020 December 7, 2020 Development: The roots or crown tissues are infected by conidia or mycelia present on crop debris. Symptoms: Aphids are nearly transparent, soft-bodied sucking insects (56). Hosts/Distribution: Mites generally are not an important problem, with the exception of the wheat curl mite, which is a vector of wheat streak mosaic virus (WSMV). Infection is favored by low soil moisture and cool soil temperatures. Hosts/Distribution: The take-all fungus displays a degree of specialization for wheat, triticale and several related grasses. These spores are transmitted to leaves by the wind or by splashing rain. Copper deficiency symptoms include the discoloration of young leaf tips, followed by breaking and curling of the leaves (98). As these spots coalesce, large blotches are formed. Affected plants show differing degrees of necrosis (93), often associated with stunting or dwarf clumping. Infected spikes tend to be bluish green in color (or darker), and the glumes tend to spread apart slightly; the bunt balls often become visible after the soft dough stage (9,10; page 11). They are found in most cereal-growing regions of the world, especially in newly cultivated areas that were previously in pasture. Tillers die prematurely or never head. One of the major practices used in the control of diseases is crop rotation. The disease is found in most winter wheat areas and in cool, fall-sown spring wheat areas. Wet weather favors larval movement and the infestation process. General requirements Wheat can be grown in a wide variety of climates but grows best in cool regions where the temperature is between 10 and 24°C (50–75°F). Main symptoms of ergot is the grains in the head are replaced by dark purple to black sclerotia. Summary of Wheat Disease Control Practices • Plant after Oct. 15. Cell enlargement, root swelling, and root branching occur as the nematodes mature. Importance: Small, localized epidemics can occur when conditions are favorable. Development: "Splotch" of winter bread wheats and durum wheats ir reported as a physiological leaf spot; the spots begin appearing during heading and increase in size and number toward the top of the plant. Hosts/Distribution: The seed gall nematode parasitizes wheat, triticale, rye, and related grasses; it affects wheat primarily. The agriculture minister further said that as a result of change in food habits, the demand for wheat in Bangladesh is increasing but the production is very low. When examined with a hand lens (10x), dark fungal hyphae may often be found on the subcrown internode beneath the old leaf sheaths. They will often have a brownish color. Disease can be controlled by planting resistant wheat varieties, planting disease-free seed and using a seed treatment prior to planting; disease may also be avoided by planting wheat early in the Fall and by shallow seeding Ergot disease Claviceps purpurea Ergot on wheat spike Wheat spikes infected with ergot Symptoms: At flowering, infected florets produce a yellowish, sticky, sweet exudate (containing conidia) that is visible on the glumes. There are two ways to access the information about pests and diseases that affect your crop: List format - list of all pests and diseases included in the Wheat Doctor. sporulation on lower leaves provides inoculum that can be dispersed by wind, leading to secondary spread of the disease. Physiological leaf spots, blotches, and chlorosis of leaves may occur for many reasons. This pest has been reported in most wheat-growing areas of the world. Symptoms: If infection occurs early in the crop cycle, pre- or post-emergence "damping off" of seedlings can result. Find out more about Fusarium and Microdochium stem base disease, and how they contribute to ear blight. The disease is more prevalent in cool, humid climates. Symptoms: Adult beetles are 4-5 mm long, have a black head, light brown thorax, and a shiny blue-green wing cover with parallel lines of small dots (65). Importance: Powdery mildew can cause major yield losses if infection occurs early in the crop cycle and conditions remain favorable for development so that high infection levels are reached before heading. Viruses multiply in the host plant, and transmission may occur via several means: by insects and mites (especially sucking insects, such as aphids), by nematodes, by seed, by pollen, by fungi, by soil and mechanically. Small plots can be harvested by snipping off the heads with a pair of scissors. The only labeled herbicide is Poast for grass management (since 2006), whose principal use is controlling volunteer wheat. Symptoms: Small, chlorotic, oval- or elliptical-shaped lesions appear and, as they enlarge, these lesions become irregular in shape. Hosts/Distribution: Most cereal crops and related species can be affected by cereal cyst nematodes. Leaf Rust (Brown Rust) Puccinia recondita Symptoms: The pustules are circular or slightly elliptical, smaller than those of stem rust, usually do not coalesce, and contain masses of orange to orange-brown urediospores. If infection occurs early in the crop cycle, the spike may be infected, resulting in sterility; when the disease is severe, entire leaves or spikes may be killed. Are generally favored by cooler, moist soils, and wet soils favor Pythium spp. The epidermis of the peduncle often becomes separated from underlying tissue. Importance: Major losses can occur, through seed shrivelling and lower test weights, if these diseases reach severe levels prior to harvest. Winter wheat is high yielding and is planted in the Fall and harvested in the Spring or Summer of the following year (depending on location). The disease is common in the eastern and central areas of the Asian Subcontinent. Hosts/Distribution: Black molds affect any kind of dead or dying plant tissue; distribution is worldwide. Hosts/Distribution: All plants can suffer frost damage, and frosts can occur in most temperate wheat-growing regions. Cysts are formed as the nematodes continue to develop into egg-producing adults. However, no major or widespread epidemics have been reported. Under favorable conditions, complete crop loss can occur. Distribution is worldwide. Nitrogen, phosphorous, and potassium are used by the plant in relatively large amounts, and therefore are the nutrients that are most commonly deficient. This pest has been reported in most wheat-growing areas of the world. The initial symptom before sclerotia bodies is honey dew symptom occur during flowering stage. 1 Table of Contents Feedback SECTION 9 Diseases Diseases can severely affect yield and quality in wheat. Some species may be found feeding at the soil surface, others underground feeding on roots, and still others feeding inside the stem. They exude drops of sugary liquid known as "honeydew", which may cause tiny scorch marks on the foliage and tends to encourage the development of sooty molds. Abnormal plant development may be due to physiologic or genetic disorders, nutrient deficiencies, and environmental stresses and irritants. The females lay small white eggs, one per stem, near the sheath of the flag leaf; the larvae burrow into and consume the interior of the stem, killing the upper part of the stem and the head. Courtesy: Pest and Diseases Image Library, Bugwood.org Indian Meal Moth The larvae of the Indian meal moth ( Figure 11 , adult moth) cause direct … It is found worldwide, but is especially prevalent in more humid and higher rainfall areas. Pest Diagnostic Lab (PPDL) for testing (ppdl.purdue. Heavy infestations can be very destructive; larvae may climb the plant and sever the neck just below the head. Importance: If infection occurs during the early crop stages, the effects can be severe: reductions in tillering and losses in grain weight and quality. The generation time is very short, and there may be 10 or more generations per year. inoculum (teliospores) on or near the soil surface germinates, producing sporidia, which are carried by wind to the floral structures. Initial infections come from contact with hyphae or ascospores in the soil. Other common wheat viral diseases include wheat streak mosaic, transmitted through the feeding of wheat curl mites; and wheat spindle-streak mosaic and wheat soilborne mosaic, both transmitted by soil fungi. By midsummer the eggs are extruded and the nematodes overwinter as eggs. Hosts/Distribution: Larvae are generally omnivorous in attacking grasses. Sharp eyespot lesions are more superficial and more sharply outlined than those typical of eyespot. Symptoms are produced on almost all aerial parts of the wheat plant but are most common on stem, leaf sheaths and upper and lower leaf surfaces. Leaf spots may also occur when cool, cloudy, and moist weather is followed by hot, sunny weather, or as a result of large fluctuations in temperature. Animal pests may be exotic animals which are introduced, either accidentally or deliberately. Harvested grain containing more than 5% infected kernels can contain enough toxin to be harmful to humans and animals. No alternate host is known. Basal stem and leaf sheath tissues, as well as roots, may turn a shiny black color (37). The disease continues to develop systemically, and the black subepidermal strips of teliospores become visible near heading. When they have completed their feeding, they descend further and girdle the stem base. Hosts/Distribution: Small, localized epidermics can occur when conditions are favorable. Symptoms: The primary symptom is defoliation of the plant. In damp weather, they may feed all day. False Wireworms; White Grubs; Wireworms; Fall and Winter Pests Aphids. Reproduction may be sexual or parthenogenic. Importance: Large areas of potentially productive land with acid soils (low pH) have toxic levels of free aluminum. Symptoms: Cereal cyst nematodes are more readily detected on seedlings than on adult plants. Development: Initial infections come from diseased crop debris in the soil, or from diseased grass hosts. He also expressed his gratitude for CIMMYT’s mitigation of the threats posed by pests and diseases, and climate information services enabling farmers to avoid crop losses in mung beans. The late-boot and seed-set stages are especially vulnerable and, in many areas, high temperatures are more likely to occur during these later stages of plant development. Infection is favored by cool temperatures during germination. For example, wheat blast is an emerging disease that will require wheat breeders to select for blast resistance while maintaining resistance against stem rust (Islam et al., 2016). Diseased kernels give off a fetid or fishy odor when crushed. Life Cycle: Adult cutworms (61) and army worms (62) are moths, and the females lay eggs on leaves and leaf sheaths near the ground. Several commercial wheat cultivars have high yield potential and have been released despite genetic flecking. Wheat stems showing lesions caused by eyespot (Oculimacula yallundae). Hosts/Distribution: The Hessian fly is mainly a pest of wheat, but it may attack barley, rye, and other grasses. Development: Root knot nematodes usually invade plants in the spring or early summer. (2010). Hosts/Distribution: The Hessian fly is mainly a pest of wheat, but it may attack barley, rye, and other grasses. Hosts/Distribution: The disease can occur wherever wheat is grown. They do not have a well-defined nucleus, nor a nuclear membrane. Symptoms: Adult mites are usually less than 1 mm long, and most of the plant-inhabiting species have sucking mouth parts. Fall-sown cereals are more commonly attacked. Smaller plots can be harvested by hand using a scythe or sickle. Stink bugs are of major economic importance in Asia Minor. Symptoms: Chlorosis of affected tissues is the common symptom. Importance: Alternaria leaf blight can be very severe if environmental conditions are favorable for disease development; major losses can result when susceptible cultivars are grown. Hosts/Distribution: Melanism occurs wherever wheat is grown, but is more pronouncee in high radiation, high humidity environments. Foliar applications of manganese sulfate can alleviate this deficiency. Importance: Usually not a serious problem; ongoing breeding efforts tend to eliminate genotypes prone to spotting. Above ground, infested plants are stunted and chlorotic. The reddish brown pupae, commonly called "flag seed" because of their resemblance to the seed of the flax plant, are oval shaped, flattened, taper to a point, and are 3-5 mm long. When present in large numbers, mites cause a silvery flecking on leaves (84). Pseudomonas atrofaciens. When fully grown, the largest of these larvae may be several centimeters long and nearly one centimeter thick. Category : Bacterial. Diseases and Disorders with Similar Symptoms There are a handful of wheat diseases and disorders that The development of a dark brown to black spot in the center of the lesion is characteristic of the disease. As the disease progresses, entire leaves, spikes, and even whole plants may be killed. Adults overwinter underneath plant debris on the soil surface, in leaf sheaths and ears of standing maize, or under the bark of trees. The number and formation of spikelets and florets, as well as grain filling, are reduced, resulting in lower yields. Symptoms: Adult stink bugs feed on stem tissue or developing kernels (59). The plant may also produce bleached and sterile spikes. Hosts/Distribution: All small grains are affected, but barley is more tolerant to high levels of salt than other small grain species. The early leaves may also be wrinkled or twisted. Aceria tulipae), has only two pairs of legs. Development: The bacteria persists in organic material in the soil. This ergot bodies were made up of vegetative strands of fungus. The disease is found in all highland and/or temperate areas where cereals are grown. Compendium of wheat diseases and pests (third ed.). • Treat seed with fungicide and insecticide to control aphids in the fall. Generic variability exists for aluminum tolerance within bread wheats and triticales (100). Meloidogyne naasi appears to have specificity for cereals and grasses, and can be found wherever cereals are grown. Gaeumannomyces graminis f. sp. Host tissue beneath the fungal material becomes chlorotic or necrotic and, with severe infections, the leaves may die. Transboundary pests have become a serious threat to food security, exacerbated by the globalized movement of people and commodities and the changing climate. Diseased glumes have a translucent appearance when held toward the light. The disease is spread by splashing rain, plant contact, and insects. Wheat will not grow at temperatures above 35°C (95°F). With light infections the pustules are usually separate and scattered, but with heavy infections they may coalesce. The larvae are found in cracks in the soil or under rocks during the day, feeding at night or early in the morning. Wheat Insect Management Guide; Wheat Variety Disease and Insect Ratings ; Wheat Stem Sawfly; Hessian Fly ; Greenbug ; Identifying Caterpillars in Wheat (1999) Russian Wheat Aphid; Biological Control of Insect Pests on Field Crops in Kansas ; Below Ground Pests. When present in sufficient numbers, aphids can cause yellowing and premature death of leaves. Importance: Basal glume rot usually is not economically important, but is frequently reported in humid cereal-growing areas. Phosphorus deficiency usually results in stunted plants with fewer shoots (96), if the deficiency is mild. Infection can occur throughout the crop cycle, but is favored by cool (12-18C) soil temperatures and alkaline or nutrient deficient soils. They have three pairs of legs (78), and their color may vary from a rich cream to shades of brown. translucens Syn. Eggs are deposited in the soil and the hatched larvae feed on roots. The mycelia often present in the centers of lesions are easily removed by rubbing. Hosts/Distribution: Leaf rust can affect wheat, triticale and many other related grasses. Conidiospores are produced in sporodochia, which gives the spike a bright pinkish color (30). Symptoms: The postules are circular or slightly elliptical, smaller than those of stem rust, usually do not coalesce, and contain masses of orange to orange-brown urediospores. Development: Sclerotium rolfsii can attack the plant at any stage of development. On the spikelets, lesions generally start at the base of the glume and may eventually extend over the entire glume (51). Spring wheat is not as high yielding but tolerated drier conditions. Alternaria, Cladosporium, Stemphylium, Epicoccum and other species. Rainy or humid weather favors the production of exudate and spores. Technically, black molds do not constitute a disease, since the fungi are saprophytic and invade only dead or dying plant tissue. Lesions are difficult to distinguish from those caused by Helminthosporium spp. List of most important wheat pests; Nematodes: About nematodes: Cereal Cyst Nematode: Root Knot Nematode: Root Lesion Nematode: Seed Gall Nematode: Insect pests: About above ground insect pests: Aphids: Stink Bugs: Armyworms, Cutworms: Cereal Leaf Beetle: Thrips: Hessian Fly: Wheat Stem Maggot: Sawfly: Grasshoppers: White Grubs: Wireworms: Other pests: Mites: Snails and Slugs Pustules also can be found on leaf sheaths, necks, and glumes (5). Bunt balls caused by common bunt in wheat. Symptoms: High concentration of aluminum will first reduce development of the roots, giving them a stubby appearance. Dr. tritici. Symptoms: Lesions caused by this disease are elongated to oval in shape and are generally a dark brown color. All cultivars of winter and spring wheat seem to be compatible hosts of the nematode. Hosts/Distribution: Though many minerals can be toxic to plants, the most common toxicity affecting wheat is caused by an excess of free aluminum. SECTION 9 WheAT - Diseases Know more. The heads of affected plants tend to remain erect and become black and discolored during ripening due to colonization by saprophytic fungi. Identification can be facilitated by determining which vectors are present and the host range; in many cases, positive identification requires the use of an electron microscope and serological techniques. When dry, the exudate is white. Hosts/Distribution: Tan spot can affect wheat and several related grasses; triticale, barley, and rye are less frequently affected. Oats are more sensitive than other small grain species. Infection and disease development are favored by cool, humid conditions, which prolong the flowering period of the host plant. The film may crack and give a scaly appearance. In some cases, diseases are controlled through simple cultural practices and good farm hygiene. Commonly, plants infected with wheat streak mosaic also are infected with High Plains disease and Triticum mosaic. Species of these insects are found in most cereal-growing areas of the world. Hosts/Distribution: Rhizoctonia solani has perhaps the widest host range of any pathogen, attacking most cultivated crops; virtually all members of the Graminae family are susceptible. Symptoms: Phytotoxicity can result from the poor application of most pesticides. Often the spikes and necks will emerge as a distorted, sticky mass (53). Mites are not insects. It attacks wheat when it comes in contact with the plant apex within the leaf whorl, and this transmission is often facilitated by the nematode A. The sclerotic interior is white or tennis white in color. Symptoms: Melanism occurs as brownish black to dark purple spots, streaks, or blotches on the leaf sheaths, stems (90), and/or glumes and results from a high production of melanoid pigments in some genotypes. Infected kernels may be permeated with mycelia and the surface of the florets totally covered by white, matted mycelia. Spotted plants otherwise are normal. Wheat is broadly categorized into Winter wheat and Spring wheat. Development: Primary infections usually are light and develop from wind-borne urediospores that may have travelled long distances. Harvesting Wheat is ready to harvest when the stalks and heads have turned from green to yellow and the seed heads are drooping towards the ground. While most of the diseases, pests, disorders, or stresses included can be economically significant, some are not and are presented only because they are unique or might be confused with more economically significant problems. In factors as nutritional deficiencies, poor drainage, and soil-borne diseases can conceal the presence of nematodes. There have been no reports of widespread and destructive epidemics. The larvae girdle the stem (73) and, later in the crop cycle, lodging is common. This superficial fungal material can be rubbed off easily with the fingers. If humid weather prevails for a few days to a week just prior to harvest, the incidence of infection will increase and black point will develop in many cultivars. The disease may develop rapidly when free moisture (rain or dew) occurs and temperatures range between 10-20C. Free moisture usually is necessary for infection, and penetration of host tissue occurs through wounds or stomatal openings. Importance: These insects usually are localized in their distribution, but can cause a great deal of damage to individual stands of wheat. Diseased tissues will frequently have white, fluffy fungal mycelia on the surface (44), which often permeate the soil surrounding the plant. Importance: Severe infections can cause yield losses, mainly by reducing the number of kernels per spike, test weights, and kernel quality. Development: Wind blown teliospores that land on the flowers of wheat plants can germinate and infect the developing embryo of the kernel. They have three pairs of legs of Wireworms are the primary infection occurred! These diseases affect all small grain cereals seed in before covering it up. Small plots can be sown by hand broadcasting in smaller areas, or the ovary.! Field make if difficult to detect, and many grasses diseases and pests ( third ed. ) several varieties! The film may crack and give a scaly appearance Management ” manganese occurs most commonly in soils that.... Than 1 mm long and are laid in rows on the upper and... 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