General Production Information

The primary production region for durum is the Northwest and North Central part of the state. Of 3,000,000 acres of durum planted in 1998, 1,520,000 were planted in the Northwest district, 410,000 in the West Central, and 370,000 in the North Central.

Spring wheat was grown statewide. Of the 6,700,000 acres of spring wheat planted in 1998, 1,250,000 were planted in the Northeast district, 990,000 in the East Central, and 830,000 in the Southeast.

Table 1. Wheat Production and its Economic impact on North Dakota’s Economy

Cultural Practices

North Dakota has a temperate climate that is conducive to growing wheat. Average annual days above freezing range from 110 days in the North to 130 days in the South. Average growing season precipitation ranges from 16.0 inches in the Southeast to less than 12.0 inches in the Northwest. North Dakota soil types range from rich organic soils in the east to lighter soils in the west. This combination of climate and soils is ideal for statewide wheat production.

Spring and durum wheats are planted in the spring, from late April to the end of May. Seedbed preparation can vary based on the type of seeding equipment used. No-till, and reduced tillage drills are designed for use in high residue conditions. Conventional drills require greater seedbed preparation. This is achieved through the use of tillage equipment in the fall following harvest and in the spring prior to seeding. Row spacing ranges from 6 to 9 inches with seed planted at 2 inch depth or less. A plant population of 28 to 30 plants per square foot is desired.

Spring and durum wheats are harvested in the fall from early August to late September. During the 1990's, durum yields averaged from 22 to 38 bushels per acre, while spring wheat yields range from 25 to 42 bushels per acre.

Hard Red Spring and Durum Wheat Processing

Hard red spring has the highest protein content of all U.S. wheats, usually 13 to 16 percent. High protein content corresponds with greater gluten content. For this reason, flour mills in the United States and in many export markets blend hard red spring wheat with lower protein wheats to increase the gluten content in flour. The addition of hard red spring improves dough handling and mixing characteristics, and water absorption.

Durum is the hardest of all wheats. Its density, combined with its high protein content and gluten strength, make durum the wheat of choice for producing premium pasta products. Pasta made from durum is firm with consistent cooking quality. Durum kernels are amber-colored and larger than those of other wheat classes. Also unique to durum is its yellow endosperm, which gives pasta its golden hue.

When durum is milled, the endosperm is ground into a granular product called semolina. A mixture of water and semolina forms a stiff dough. Pasta dough is then forced through dies, or metal discs with holes, to create hundreds of different shapes.

Durum production is geographically concentrated to North Dakota and the surrounding area because it demands a special agronomic environment. North Dakota produces 73 percent of the U.S. durum crop. Many international and domestic millers prefer North Dakota durum for its color and strong gluten characteristics.

Insect Management

Insecticides were applied on 4% of the wheat acreage in 1996. Starting in 1996 the wheat midge had a significant influence on insecticide usage. Approximately 500,000 acres were treated with chlorpyrifos, the only registered insecticide for wheat midge. Other products used were lambda cyhalothrin, carbofuran, carbaryl, and ethyl parathion. The most frequent target pests for these products included grasshoppers and cereal aphids. A total of 541,500 acres were treated with insecticides. The producer applied 22% with ground equipment and the remaining 78% of treatments were aerial applied.

Aphids: Greenbug (Schizaphis graminum), English grain aphid (Sitobion avenae), Bird cherry oat aphid (Rhopalosiphum padi), and Russian wheat aphid (Diuraphis noxia).

The English grain aphid, bird cherry oat aphid, and the greenbug are the most common aphid pests of small grains in North Dakota. The Russian wheat aphid has only been a minor pest in the state. The greenbug and the Russian wheat aphid are considered to be the most injurious of the aphids. During feeding these aphids inject saliva which is toxic to the plant causing yellowing and death of leaf tissue. Large populations of bird cherry oat aphid are associated with high infection levels of Barley yellow dwarf virus.

Problems with cereal aphids are dependent on when they migrate into the region, weather conditions when they arrive, and growth stage of wheat when populations increase. Aphids are present in wheat fields each season. Aphids are usually the most troublesome during periods of cool, wet weather. Late seeded crops are likely to be most severely infested. Growers are discouraged from appling excess nitrogen, since excessive plant growth will promote aphid infestations. Most infestations are minor and are kept in check by natural enemies such as syrphid fly larvae, aphid lions, ladybird beetles, several parasitic wasps, and parasitic fungi. When natural enemies are present in large numbers, farmers are discouraged from spraying insecticides.

Orange Wheat blossom Midge: Sitodiplosis mosellana

In recent years the orange wheat blossom midge has been a cause of economic concern. In North Dakota the wheat midge has been detected in all counties north and east of the Missouri River. Significant damage has also been reported in Minnesota and the prairie provinces of Canada. Damage caused by the wheat midge is difficult to detect. The wheat plant is only attractive to the wheat midge from the time the head emerges from the boot to flowering. At this time female adults lay their eggs within the wheat head. After hatching the midge larvae feed on the developing wheat kernels causing them to shrivel and become deformed. Only by examining the kernels can damage be found. The wheat growing areas of Northeast and North Central North Dakota have been the areas most heavily damaged. However, other regions of the state have had populations of wheat midge which warranted control.

Wheat midge populations have been partially held in check by a parasitic wasp called Macroglenes penetrans (Kirby). This wasp can control up to 50% of the overwintering midge population each year. Rotating wheat with other non susceptible crops aids in reducing wheat midge numbers. Crops such as oilseeds, barley, and oats can be grown with little or no risk of damage. By selecting early maturing varieties and planting early, the wheat crop will head and flower before the peak of the wheat midge emergence.

Current treatment recommendations are when one or more midge are observed for every four to five wheat heads. Treat only when 75% of wheat heads have emerged from the boot. Treatment after 50% of the wheat heads have flowered is not recommended because of reduced efficacy and for the protection of the parasitic wasps.

Grasshoppers: Clearwinged grasshopper (Camnula pellucida), Two-striped grasshopper (Melanoplus bivittatus), Migratory grasshopper (Melanoplus sanguinipes), differential grasshopper (Melanoplus differentialis), and Redlegged grasshopper (Melanoplus femurrubrum).

Grasshoppers are sporadic pests in North Dakota, especially in regions that receive little rainfall. Weather is one of the main factors affecting grasshopper populations. Outbreaks are usually preceded by several years of hot, dry summers and warm falls, allowing populations to increase. Damage to wheat is usually concentrated near field margins. Individual plants can be damaged by leaf stripping, awn loss, head clipping, and damaged kernels.

Natural enemies include parasites, predators, and diseases. Some type of natural enemy attacks all grasshopper stages. Early seeding establishes vigorously growing plants that are more tolerant to grasshopper injury. Early seeded crops will mature earlier and reduce the risk of late season migrations of adult grasshoppers. Crop rotation, tillage, trap strips, and harvesting crops early are other cultural control practices used to reduce grasshopper damage. Grasshoppers are more easily controlled in the nymphal stage. Treatment is advised when 50 or more nymphs per square yard are found in field margins or 30 or more nymphs per square yard are found within the field.

Armyworms: Pseudaletia unipuncta

Outbreaks in North Dakota occur when large migrations of moths from the south occur in late spring and early summer. Armyworms feed at night on above ground vegetation, and hide under the foliage and in the soil during the day. In most years, populations are kept low by unfavorable weather conditions such as cool wet weather.

A number of diseases and parasites attack armyworms. Tachinid flies, parasitic wasps, and viruses are all natural controls of the armyworm. These natural enemies often do not destroy armyworm larvae until after severe crop damage has occurred. Their greatest impact is preventing excessive increases in the next generation.

Current treatment recommendations are when four to five or more worms per square foot are present.

Cutworms: several species (Lepidoptera: Noctuidae)

In western North Dakota, the pale western and the army cutworms are important pests of small grains. Pale western cutworm eggs hatch in the spring, and the larvae feed below ground cutting plants over at ground level. Army cutworm eggs hatch in the fall and the spring, larval feeding is above ground. The dingy cutworm, red-backed, and dark-sided cutworms are common but wheat is not as frequently affected as the regions field crops.

Wireworms: (Coleoptera: Elateridae)

Wireworms are a minor pest of spring and durum wheats in North Dakota. The wireworms or click beetle larvae live for two-nine years in the soil. They are attracted to carbon dioxide, which is released by germinating seeds and growing plant tissue. Wireworms feed on the seeds and roots. Damaged plants are then more susceptible to plant pathogens.

The only insecticide registered for wireworm control is lindane. Lindane is applied to the seed just before planting. Lindane can be purchased as a dry drill box treatment or as a liquid formulation.

There are multiple minor insect pests present in the region. These include: wheat stem sawfly, Cephus cinctus, wheat stem maggot, Meromyza americana, and Hessian fly, Mayetiola destructor. These insects are managed most effectively through cultural practices. Insecticidal control has not proven adequate for these pests.

Table 2. Registered insecticides and their usage in North Dakota to manage wheat insect pests.

¹ Zollinger et al, 1998.
NR - Use not reported by survey

Disease Management

Several diseases are potential problems on wheat every year in North Dakota. Cool moist soil in the spring slows the growth of wheat and promotes the growth of diseases. Prolonged exposure to dry soils can also hinder germination and promote diseases. Foliar diseases can also be a serious problem in North Dakota. Disease causing fungi can survive in crop debris, field trash, and sometimes seeds. Usually a prolonged period of high moisture and humidity is required for disease organisms to infect growing wheat fields.

Wheat diseases are best managed with a combination of cultural and chemical controls. Rotating other crops with wheat and burying crop residue are examples of cultural controls. Treating wheat seed in the spring with fungicides and during the growing season with foliar fungicides are popular chemical methods for managing wheat diseases. The most commonly used fungicides on wheat in North Dakota in 1996 were: Benlate, Mancozeb, and Propiconazole. In 1996, 279,200 acres were treated with these fungicides, or just over 2% of total wheat acres in the state.

Fusarium head blight (Scab): Fusarium graminearum and Fusarium culmorum

Repeated scab epidemics and large economic losses have resulted from Fusarium head blight infections during the 1990's. Scab is a problem when long periods of high humidity and wet weather occur at heading and grain-fill. Parts of the wheat head become infected; often kernels infected are pink in color at their base. Scab can severely reduce yields and test weight. Additionally, infected seed may contain fungal toxins to which afect feed and food quality. At this time scab is the most serious fungal disease in small grains in the Upper Midwest.

Growers are encouraged to reduce the risk of scab infection through crop rotation, avoid planting on last year’s corn ground, and use tillage to bury crop residue and trash. Scabby grain should not be used for seed. If scabby grain is used for seed, it is recommended to treat the seed with fungicides, such as carboxin + thiram, Maneb + imazalil, or difenconazole. If favorable weather occurs at flowering, some foliar fungicides have been demonstrated to reduce scab severity.

Table 3. North Dakota Section 18 and 24C emergency fungicide exemptions for wheat protection from Fusarium head blight, 1998 - 2000.

Observations from research results and commercial wheat fields indicated the following:

• The two fungicides, applied at heading with angled sprays, resulted in +11.9 bushels yield and +1.3 lb. test weight for tebuconazole, and +8.9 bushels yield and +1.0 lb. test weight with propiconazole on treated wheat acres.

• On treated acres, increased yield from fungicide use was +11.3 million bushels of wheat. Total economic gain was $33.9 million dollars, based on $3.00/bu wheat and yield response alone.

The total cost of fungicide application for both fungicides was $14.00/acre, or $14 million for the 1 million acres treated. Total economic return for wheat producers in North Dakota and northwest Minnesota in 1998 from use of the Section 18 and Section 24C fungicides and their improved application showed a $33.9 million return - $14.0 million cost = $19.9 million dollars

Wheat Leaf Rust: Puccinia recondita f. sp. tritici

Spores of the rust fungi overwinter in southern states and are carried to North Dakota by the wind. Leaf rust is recognized by reddish-orange pustules found on the leaves and stems of infected plants. Each of these pustules is capable of producing approximately 1,000 spores. Each rust spore is able to infect a new wheat plant. The growing spores deprive the host plant of nutrients.

The use of wheat varieties resistant to rust limit the infection, retard fungus growth, and limit spore formation. However, recent shifts in leaf rust races have resulted in many varieties losing their resistance, and now most varieties grown are susceptible to one or more of the prevalent races of leaf rust. Fungicide sprays containing mancozeb, propiconazole, or triadimenfon can control leaf rust. Applications should be made at the early boot stage for mancozeb products, at flag leaf emergence for propiconazole products, and the early boot stage for triadimenfon products.

Leaf diseases:

Tan spot, Pyrenophora tritici-repentis, Leaf blotch, Septoria species, Spot blotch, Helminthosporium sativum, and powdery mildew, Erysiphe graminis f. sp. tritici, are common leaf diseases in wheat in North Dakota. If enough leaf surface area is killed, grain yields and test weights are reduced. Fungi overwintering in crop debris and trash promote the development of leaf diseases. Most of these diseases require long periods of high moisture and high humidity for infection to occur.

Crop rotation, and spring tillage with the purpose of burying crop residue can reduce leaf diseases. Foliar fungicides containing Mancozeb or Propiconazole are effective against foliar leaf diseases.

Loose smut: Ustilago tritici

All wheat and durum varieties grown in the state are susceptible to loose smut. Generally, smut is not a severe problem, but the reduction in use of seed treatment in recent years has resulted in increased numbers of fields with economic losses due to loose smut..

Crop rotation is recommended for reducing the risk of infection. Applying the appropriate seed treatment containing carboxin, difenoconozole, or triadmenol will protect the wheat crop from loose smut.

Common root rot: Fusarium and Helminosporium spp.

This is a potential problem every year in North Dakota. Damage is often most severe when the crop is stressed. Root rot can be identified by brown discoloration of the roots and crown, and wheat heads having fewer seeds that may be shriveled.

Crop rotation is recommended for reducing the risk of infection. Seed treatments containing difenoconazole, imazalil, and triadmenol are registered for suppressing root rot.

Take-all: Gaeumannomyces graminis var. tritici

Take-all is a serious root rot which can completely destroy a crop. It is most common in fields of continuously cropped wheat and high soil moisture. Damage is characterized by a black shiny discoloration at the base of the plant.

Wheat should not be planted on a field having take-all for three seasons. Seed treatments containing difenoconazole and triadimenol are registered for control of take-all.

Glume blotch: Septoria spp.

The glume blotch fungus has been endemic in wheat in North Dakota, causing slight to moderate damage. This fungus has contributed to low yields and test weights in recent years especially in durum. This fungus survives on wheat residue, and infection is favored by warm, wet weather following heading.

Crop rotation and tillage practices aid in the management of this disease. Foliar fungicides can help protect against leaf infection. Benlate, when used in a tank mix with Bayleton or Manzate 200, and mancozebs are registered for glume blotch control.

Wheat streak mosaic:

Wheat streak mosaic virus (WSM) causes severe yield losses on wheat some years. The wheat streak mosaic virus is carried by the wheat curl mite. The mite lives and reproduces on wheat and other grass hosts. It survives the winter on seeded or volunteer winter wheat. Symptoms of wheat streak mosaic often appear at the edges of the field first. Infected plants are yellow and stunted, and almost no growth occurs. Diseased plants often don’t produce heads; if heads are produced they are often sterile and do not produce seed.

To reduce the risk of WSM, destruction of all volunteer wheat in fields before planting winter wheat is recommended; volunteers act as a reservoir for the wheat curl mite. Winter wheat should not be planted too early; planting early increases the chance of infection by the mite. In the spring, any infected winter wheat plants should be destroyed or they may become a source of infection for spring planted wheat.

Table 4. Registered seed treatment fungicides and their usage in North Dakota wheat production.